I learned there is such a thing as a divided queen mattress, so I'm building a bed platform that will work with a divided queen.
I roughed out the bed platform. It's in two halves which stack.
Stacked, seen through the back doors:
There's plenty of room to use the space for cooking and eating.
Pulled out:
There's about 6" room beside the bed when fully opened. Several feet on each end of it. I believe tomorrow I'll trim the fixed platform about 3/4" shorter to make them stack better, and I'll add some reinforcements here and there.
Once that's done, I just need to get a divided queen mattress.