Duro: looks like my shop and garages at times and currently. I've figured out that until i get out of the city and buy a bigger piece of property to have a nice shop that putting lawnmower and extra tool boxes against a wall that i always can use the space above it. sometimes you can put these heavier duty racks in between the cars too.
since the heavier duty racks don't need a shelf on the ground or just above to keep them solid i usually set at about 3.5 feet off the floor so the lawnmower or rolling toolboxes can be rolled under them with storage above. just one idea that might also help you.
if you have any questions just ask and for this 19.5 foot wide shelving setup it took 2 of the heavier duty shelving units Costco sells for about $150 each. i still have some of the 4 foot wide shelving, but i'll probably change that out eventually.
I've bought this green and orange very heavy duty shelving for my storage and outside that works well and especially if you have tall ceilings. it comes in 2 to 4 foot depth and many widths and heights.
again welcome to our forum