Looking for mattress replacement for Flagstaff pop up

We also just added a foam topper to ours. We only had room for one that was 1.5" thick and even with that, I have to let the roof settle a little before I latch it down. It made a huge difference in comfort. Before you replace or add, be sure how much room you have to work with once the roof is closed.

I've also heard of some just replacing with air mattresses and deflating them to lower the roof.