I get by with a camping cot and an air mattress. I don't even want to think of a waterbed and the issues that brings to the table. And here I thought it was something to have several batteries, a refrigerator and a TV, with all the weight that represents.
Something to consider if you're driving a CV/Sprinter: Anything that you bring along as part of your "house" adds a certain amount of weight-- which in the trade we call "tare weight" to your vehicle. You already have only a limited amount of payload weight to begin with, so any and all tare weight chews into that. A waterbed can weigh an enormous amount, and that weight comes right off the top of what you can haul to begin with. Turtle carries four batteries in his "house battery" package and that's close to 400 lbs right there. Add a refrigerator and a TV--- and before long you've got a great RV but a terrible expedited vehicle. It's a balancing act, and that means we do without a lot of stuff we thought we couldn't live without until we started doing expedited in vans and had to make do with limited space and limited weight capacities. Think like a camper that will have to carry all you need on a backpack: Start trimming everything you don't have to have, and make what you do have to have as light as possible.