I am experimenting with ditching the standard foam mattress in favor of a Thermarest
Luxory Map pad. I tried this on a 10 day trip to Utah this spring and was satisfied. The pad is 3 inches thick and has an R6 rating. We’ve placed 2 of them side by side which requires the extended bed out by at least 6 inches.
The 48 inch bed in our ATC Panther is a bit too tight and carrying the 2 extra cushions can be clumsy. The R6 insulation value and ease of dealing with any condensation issues are pluses. So is the ability to easily remove the pads for cleaning etc.
I find the pads to be comfortable, I am 5’9” and 165#.