For what it's worth I bought this 10" mattress and was still happy enough with it after two five months stints of boondocking that I bought another one to replace the mattress at my cabin: Best Price Mattress Memory Foam 10 Inch Mattress, Full
https://www.amazon.com/dp/B00GTCL2FU..._eM1CCbGPW2YW3
For reference, I'm about 5'9" and 155# and a side and back sleeper.