Not in order.
Furnace as far from bedroom as possible.
Large battery area with for 6 volts if boondocking much. Hold four 6s.
Large tanks.
One dump outlet.
Curved roof, not flat.
Thick floor wood, not sandwich foam.
Don't worry about solar pre wire. Good chance you would want heavier wire.
Heavy frame style. Some are welded sections. Search frame issues.
Wet bolts.
Ease of use with slides in.
Light switches. Not having to reach to the fixture.
Television space. Sure a 19" will work but sometimes you like a 40 or more.
Furniture comfort . How long could you really sit on the couch or dinette.
Window blinds. Regular old blinds are surprising cheap easy and effective.
How easy would it be to remove the carpet and install other material.
Where is the fridge located. If you wanted to install a resi is there room for door swing and possibly hog out the cabinet.
Refrigerator venting for propane fridge, in slide?