My dream was to sale our 3,200 sq ft house, purchase a MH and build us a small 30 X 20, one room home in our town. It would have a bedroom sectioned off from the main living area by the bathroom and large closet.
That dreamed died quickly when our daughter was born 27 years after our son and then another daughter came along 3 years later.
So, now we have a 322 sq ft fifth wheel that we travel in from May until September and then go home for the school year. It works great and has given us a lot of enjoyment. We are still planning our trip for out west and then to Alaska. We'll probably do "out west" next summer.
Whatever you go with, make sure you have storage room. You can get away with less "living" room since you can go outside, but you have to be able to store stuff out of site or at least out of your way. That also can be accomplished by a storage shed with room for a washer/dryer.