I think you need to give us more information.
Are you going to be able to keep dust and stuff out of your paint job on your carport? Do you care? When do you plan to paint. Paint likes warmer weather than we are having around here so inside just might be a good idea. But then, do you have a way to exhaust the bad vapors and such from your garage? Is your house going to smell like a spray booth? I did that once. Are you painting a complete vehicle at once or have you exploded your ride? That would help you decide how much room you need. Good luck.

Six volt guy living in a twelve volt world