I can tell you about land development, zoning, and regulations in Florida. Much of this information is broadly-applicable across the country, but as has been mentioned, your local AHJ is 'he/she who decides all-issues.' I have worked as a plans examiner, a zoning person, a planner, lifesafety inspector and assistant fire marshal.
I have a number of friends who have worked or who do-work in the trades, for various levels of government, as code administrators, inspectors, and plans examiners, as G.C.'s, etc.
The solution is really very-simple: comply with code. As you mentioned, sometimes getting to the heart of the matter is a roundabout journey. It sounds like your efforts to this point have-been well-intentioned, and I see a bit of frustration.
Take things systematically. Read the codes which apply to your area, your geographical area, and your intended area of operation. Remember that the thing which controls your property is its zoning, and then its usage/occupancy. There are other factors which may come-into play, and as you become more-familiar with your local regulations, and the people who enforce them, you will have a better-chance of getting the OK for what you want to-do if you comply with code.
Before you consider the purchase of any parcel whether bare of development, or which has improvements to-include a building or buildings, you have to know the zoning, and the zoning code will narrowly and specifically-define what you're entitled to do there, and for-what uses the occupancy can be operated.
If your scope of work is outside of what you intend to-do there, do not assume that you can make an 'end-run' around the ordinances, regulations and codes. You could find yourself facing a per-day fine situation, and I often saw these accruing quickly into the tens-of-thousands of dollars, or six-figures for residential situations, even-more for commercial or for industrial occupancies.
Don't believe, "I can do part-of what they want, and as I make some $$$ here, I'll come-into compliance with the rest." You won't be-able to earn a certificate of compliance, a certificate of occupancy, a business tax receipt (Florida's term for permission for a business to-operate, formerly called a certificate of use), or whatever other paperwork is required for your use of the property. You've already-mentioned about "accessory uses not being allowed in a residentially-zoned property, without a complying residence." That's common.
Say that you found a parcel. Nothing exists now in the way of improvements. If it's AG (agricultural zoning district) the permitted uses are more-numerous, with the expectation that the uses are agriculturally-related. Raising miniature horses, growing crops, roadside sales of fruits and vegetables, repairing farm equipment and associated vehicles contributing to legal occupancy of the residence (that could be your 2-post lift for your Boss 302), all are probably-allowed under that zoning.
If you want to have a business repairing muscle cars on an AG-zoned parcel, you'd better read your local zoning code to see if you are allowed to do that and to do hot-work, to have a spray booth, since those are typical uses for that type of occupancy. These days, operating a spray booth has all-sorts of environmental considerations it has to-meet, and the probable path to legally-operate, requires having to-spend tens of thousands of dollars for a licensed spray booth meeting OSHA, EPA and NFPA regulations. Better-to be able to legally-paint smaller assemblies, and to leave the body color painting to a pro installation.
Running a business, there are five areas of operation that are reviewed in a zoning application:
use
parking
landscaping
lighting
signage
These are usually shown on a site plan, where each in-turn has a page or pages devoted to the subject.
The use intended is described in the zoning code and by the applicant as being narrowly and specifically defined. A crematorium, a business office, a paint store for paints used in construction and/or for vehicles and equipment, a rental storeyard for construction equipment such-as backhoes, bulldozers, cranes, etc.; a vehicle repair facility (what-type of repairs is often specified, as-is what would-not be allowed; a pig farm, an animal rendering plant, the list goes-on. In some cases, uses will include uses concurrent with operation of the primary occupancy, i.e., a construction equipment rental business/storage yard will also allow repairs on the equipment. The work may have specific requirements: a cab-for-hire business may allow vehicle repairs but require all repairs to be performed inside a building, and may exclude bodywork/painting.
Parking requirements are often based on the number of people who arrive at the business. Restaurants have capacity seating based-upon square footage, aisles (a seating/table plan is required, showing paths of egress distances); doctors' offices may be based on the number of examination rooms, and office space; mercantile businesses based upon the square footage open to the public, and another value for storage square footage; etc.
A single-family dwelling will have simplified versions of this. Parking is required for two vehicles on an improved surface, with a minimum radius for turning, if necessary. Curb cuts are limited in dimension and in placement (proximity to an intersection, site triangles).
Landscaping often goes hand-in-hand with parking. Is head-to-head parking allowed, or are landscaped, sprinklered islands defining parking in groups of not-more than 10 spaces the requirement? The parking site plan will show this. Lanes for queing are required for certain businesses, like banks with drive-through ATM's, or fast-food restaurants. These often have a mandatory requirement for a 'no-roof' lane, allowing tall vehicles like trucks to safely pass-through, without contacting the porte-cochere. Certain trees and shrubs may-be required, such-as native species, drought-resistant, salt-tolerant, no pest-species plants, and also observance of 'right tree, right place.' In south Florida, you would not want to be planting a Royal Poinciana tree, which often has a canopy when mature of 40 ft width, in a parking landscape island.
Lighting/illumination requires a site plan showing placement of luminaires, and a photometric survey of the predicted illumination values taken at a certain distance above grade.
Signage for businesses, including home-based-businesses, is prescribed as-to placement, size, illumination, colors, and features like movement (think of those air-filled constantly-moving 'stovepipe' men). Channel letters, monument signs, window signs, raceways, neon, and other types are described as-to whether they are allowed, and their placement. Temporary sales signs and promotions are described as-to placement, location, and duration of use.
Do you have a specific question related to a proposed use? You can formally-submit your written question and receive a 'zoning determination letter,' and this will tell you what you need to-know, which may help you to immediately see that your proposed use is not-allowed, or it is allowed. This document may-be called something different. There is usually a fee for this. An informal question on interpretation of the zoning code may-be answered by a staff member, it's usually good to have the specific part of the code in-hand, remember the lawyer's adage, "never-ask a question to-which you do-not know the answer."
If your desire is to have storage for your vehicles and a boat, don't think that you can open a vehicle repair shop and have customers' cars parked awaiting repairs in an area zoned single-family dwelling, 6 units/acre.
The info I included is more-for commercial occupancies, or industrial occupancies. Just remember that once you're on the radar of the AHJ for being in-violation of local codes, the observations of your behavior will continue. If you are found in-violation, you could be fined, and the fines may not-stop until the property is brought fully into compliance. If you are fined, and the fine accrues to a large amount, you may-be eligible to request mitigation, a reduction of the amount you have-to pay, based upon your willingness to comply, and the timeframe in-which the compliance occurs. It's not-uncommon for a timeframe for compliance to be given, and if you meet it, no-fine.
If you do ever get a notice of violation or a citation (the citation here is an immediate fine) do not neglect to immediately contact the person who wrote it, to discuss the matter, and remember, the goal of the staff is to get you to comply with code.
