WASURF63
Adventurer
We added a memory foam mattress pad to our FP for a while. We would slide it up onto the fully extended/stretched hammock then close the FP. When we opened it up when camping we would just slide it on top of the regular FP mattress before moving the poles over for the hammock and access to the bed. The FP was only slightly more difficult to squeeze shut and we had a double thick mattress that took no additional space. Unfortunately the memory foam 'forgot' it was a mattress and we returned it. If you're using bedding instead of a sleeping bag, this is an option for storage that takes up no additional space.
Tried the same thing a while back. It made the mattress more comfortable, but was also more difficult to close the top, and left an approx 1/4" gap in the rear seal, creating more exposure to the elements.
Solution: 1) stack another layer of bulb seal or 2) omit the memory foam pad.
*Trying to stow a dbl sleeping bag (w/o addl pad) in the same fashion lead to the same result. I chose option #2.