The problem you will have with OSB and 1/4 inch plywood here in GA (I am near Augusta) is warping from heat and humidity. I used 15/32 plywood sheathing on inside walls and 6" insulation to reduce warping and give me a hard surface to hang what I want. I have metal rafters and metal roof with...
I used auto hobby shops all over the world. They are a great deal especially since you can do nothing on a car in base housing. They are subsidized by NAF. Mostly profit from bx/px and commissary.
Atlanta Motorsports Park. Subdivision part is a long ways off. Supposed to be open for racing this fall. Memberships are still available for those with a high tolerance of risk and lots of disposable income. Houses bordering property are available cheap...
It is a tough business model.
The "Auto Barn" option with a few bays for contracted storage customers is more likely I would think.
I have used a lot of military auto hobby shops - they are mostly good, not always cheap, and tool control is rarely a problem.