Greetings!
In my current rig, I have a normal house style futon sofa/bed. I extended the legs using telescoping metal conduit, designed to work similar to adjustable cabin tent poles, to raise it up over the wheel well, and also allow me to level it if I’m parked on uneven ground. Simple and effective but basically fool proof.
When I’m alone, I usually just sleep on it in sofa mode, and since I don’t typically use it for seating, I just leave my bed ready to crawl into, with no set up necessary. If I’m having company, I can remove my bedding in seconds to create extra seating. For a sleep over it will convert into a double bed.
I prefer a permanent bed set up, and separate seating. I have an old, super comfortable, swivel, rocking, reclining desk chair to lounge or work from. Comfortable enough to sit in all day long, or even fall asleep in. I have a 12v heating/cooling/massage seat cushion in it, as well as one in my drivers seat, and a 3rd spread out under my sleeping bag on my sofa. Talk about comfy… they make a world of difference. You can find the most amazing things at truck stops, including these and 12v heating/cooling blankets which I also use and love. They use very little power, and mine have thermostats to hold the temperatures exactly perfect. Both types are cheap, only about $20 each, and worth every penny.
I’m currently in a 1973 Dodge Travco high top camper van that had been gutted before I purchased it. I restored the original carpet & padding, wall & door panels, and window trim from passenger vans in wrecking yards, then moved my new new furniture in and secured it, rather than actually building it in.
Cheers!