I was thinking about something very similar. My car is over 18 feet long, and I am looking for a place to buy. The problem is I'm not findng anything that has a garage more than 21 feet, which makes getting my car in and out of the garage fun. On top of which, I can not put anything on the walls there. I have a huge Snap-On tool box, and The math just does not work to allow me to have both in the garage. So, I was looking at finding a builder that would allow me to work with the plans a little bit and make a place for my tool box that would allow it to be more or less recessed into the wall. More just an area that we could lose about 3 feet of depth to make basically a closet with no doors for my toolbox.
I thought it would look pretty nice personally. But, then I realized I have wayyyyyyy to much stuff to ever even come close to shoving in a 2 car garage. (3 cars, Big tool box, Brake lathe, drill press, chop saw, transmission table, etc) So, now I'm looking into just renting a place, then maybe I can open a little shop or something.