RV Garage Advice

Thanks everyone for all for the replies! The largest I could go would be about 30'x40' due to yard size. The house is brick, so I'd prefer to stay with that, but I'm sure this will add significantly to the cost. I don't need it finished inside, I can do that at a later date. I would like to have power run to it, but plumbing won't be necessary. Just a 4/12 roof would be fine, unless someone has a suggestion for something else. I didn't think about making the ceiling high enough to get on the roof while still parked inside, thanks for that guidry.