A couple of years ago we had looked at possibly getting a TT to travel with DW's mother who was basically wheelchair bound. Keystone had offered some models in their Outback line that had front ramps and a bunk area as well as a larger one with a king rear bed.
You may want to look at those, there are some other sizes on the used market from past years as well but here are some links.
Outback 324Outback 240Outback 335Or you may find something in the toyhauler lines.
If nothing else the front ramps may give you some access ideas.
Good luck
