[gmferg]

With the shells collapsed, there is limited clearance between the top of the mattress and the ceiling of the shell. It varies with model and year of TM. I can tell you with our 2008 2619, there is no clearance above the rear bed and rear half of front bed. The rear shell folds down first and the front shell folds down on top of the rear shell. The florescent lights on the rear shell actually press into the OEM mattresses slightly. Since the rear shell only covers half of the front bed, there is more headroom for the front half, probably about 6-8"

We added a 2" memory foam and 1" egg crate all contained in a zippered cover. For the rear bed it has to be totally removed and folded up on the floor. For the front bed, we simply fold the topper in half towards the front and leave it in the bed. This places the topper in the extra space that is ahead of the rear shell and below the front shell.

As you have probably already read in the other posts on the subject, some people have gone the route of an aerobed replacing the OEM matress. This has to be deflated every time you fold up.