I added 3-inch FOAM on both tent bed ends...
This brought my beds right up to the ceiling when the roof is down... Be sure you have NO CEILING LIGHTS that may come 'ON' as my three ceiling lights assemblies actually make a depression into the tent bed foam... If they were allowed to come on when the roof is down it would most certainly be a fire hazard...
My POPUP trailer has a ceiling lights AUTO DISCONNECT push button switch when my fold over kitchen has been folded over for travel...
Speaking of the tent bed mattress I added those 2-FOOT stick-on CARPET SQUARES (LOWES) under both my tent bed mattress... Really helped out making it real cozy sleeping...
Roy Ken