I ended up going with a Denver Euro top matress. It was kinda hard to choose as there were a few recommendations. I have slept on it about 5 times and it was a good rest. I chose this one because it's not so thick that it won't fold and fit when upright. It does fit well. Sometimes I have to push it down just a little as i fold it up. Overall, I am totally pleased. It's not hard/firm and not too soft. Be sure to shope around for best prices. I do store and travel with it down just to keep the bed flat as much as possible.
https://www.etrailer.com/RV-Mattress...22137338105018
Hope this helps.
This little camper offers a lot. We really do love it. Even after buying it we looked at a 32ish foot Winnebago and we realized the mico mini can get in tp more places plus the heater and AC were great and the shower was hot and enough space.
I did have about 5 things that needed to get fixed pretty much right away and then everything was fine.
I also did some upgrades. Replaced the ceiling lights with 2 color, amber and white. Replaces speakers and wow, did that make a difference. And, I did get 3 days off grid with AC running a few hours a day. I ran it down to 20% once, 10%. I did get a generator and it fully charges within an hour or so.
Best to you in your purchase.