[IWillForgetThis]

Or even separate twin xl mattresses (and box springs if applicable) with a strap kit and shared king fitted sheet. My wife and I did this about 2 years ago and it's been great. She wanted a traditional mattress and I wanted to diy a memory foam mattress with a 6" layer of memory foam* (2-4 is normal). I sink into my viscoelastic cocoon every night and she sleeps on top of a normal mattress.

*Note that this is usually considered uncomfortable and possibly bad for your back. I'm a side sleeper who always had elbow and shoulder pain in the morning and it worked for me, but do your research if you ever decide to diy a mattress. It also weighs about as much as a dead moose.