I don't think your going to find one with a removable wall that's not bigger than you want. I know I've seen one out there not sure who it is at the moment but it is a 40ish ft long 5th wheel. Most all of the haulers with a separate garage are going to have that wall sealed so cold and or fumes don't get into the living space. You might be good with something that has a 10ft garage, when the garage gets bigger the hauler usually gets bigger too. If your planning on a truck also, 3/4 ton diesel would be min in my opinion or even a 1 ton SRW truck.
