Stop in for a cup of coffee

If you were to build a 1 car work space, due to limited space. What size would you make it so it would fit at least a B body and still have room to work around the front and sides?
Take the dimensions of the body and add 6’ in every direction.

That makes it 20’ wide and 30’ long.

Minimum would be 16’ x 24’...and I do mean minimum.