comments:
Don't look at RV mattresses. Mattress toppers also suck but they're better than nothing if you're on a budget. Get a real mattress, any kind you like. I have a 10" memory foam from Ghost Bed (it's $150 more now than when I bought it). I would have gotten something cheaper if I could, but I needed a short queen and there aren't as many brands making those. Side note: short queen beds suck if you're over 6' tall.
The best RV mattress is not an RV mattress, it's a regular one. If you need an unconventional size or need it to fold or work in a Murphy bed, that might limit your options. I have a 10" memory foam "RV mattress" from Ghost Bed because I needed a short queen, and there aren't a lot of short queen options. If my RV had a full queen bed, I wouldn't have bought anything labeled "RV" (where you're just paying a premium for the marketing). It's the third-best mattress I've ever owned—after the 16" memory foam king in this house I'm currently renting and a 12" Tempurpedic queen I had years ago. Don't limit your search to "RV" options unless you have to.