Every Roof Top Tent user wants to sleep on a thick mattress, Our experience is that at least a 6 inch mattress can have that kind of comfort, but such thick mattress can hardly left in RTT and close easily.
So we kept trying so many different air mattresses, seriously consider the thickness, We have been looking for an air mattress that is light and thin, easy to use, does not leak air after inflation, has a certain thickness, and can be left in Roof top tent without affecting the volume after deflation.
Most air mattresses leak after a period of time, until we talked to Dan, our friend in San Francisco, he has been use this air mattress for Adventurer XL Roof Top Tent for a year, still work good. he said:
When deflated, it's paper thin so it can easily stay in the tent. It has a built in foot pump, or you can use a cheap battery operated pump and fill it in about 10/15 seconds, We haven't had any leaks at all after use it for a year, It fills and deflates super fast and it's very soft, wish they had a wider model for Adventurer XL Fold-out RTT, but for two people it's perfect.
But if it is still not good enough, we would recommend you this mattress(QOMOTOP self inflating mattress) our Centori guy tested and say it is very good, and this kind of mattress is widely used for Foldout style Roof top Tent user, like Ikamper etc. Now it is $129(80”×52”x4'' when inflated, 80”×52”x2'' when deflated)
but price changes.