How about this?
The MH bay is 4' lower than the main level of the house.
Ceiling is 12' on the left and 16' on the right.
Door pivots on 2" pipe nipples threaded into floor flanges and is made out of 2x6 with insulation.
On the right side there is a set of steps and a door that goes into the LR/Kitchen area. When no longer RVing I will put in a false floor 4' up (same level as the house) and the outlets are already at the correct future height. At the far end there is a Atrium door that will open to the enclosed sun room. Have 100 amp service plus water and sewer for now and later.
OP, you should have requested that it be on a lake too.:B
Yes, I designed and built it myself.