I'm considering a moving bed that can come down to loft height for sleeping and be raised up out of the way at other times, but I haven't even begun on my build due to a prior landscaping commitment. Good luck with your build.
I plan to do something similar with my own van - something with a garage for my mtn bikes, a place to sleep, a place to shower inside and a place to s.... ...poo. As well as a minimal kitchen and desk space.
I have a rough idea in my head. I just need to get it down. Some of the RV van companies have done hide-away inside showers that look interesting.