I made an air pillow once with a roll top, thinking that a dozen rolls ought to keep air in. It stayed up for a couple of hours but was always flat in the morning.
Thermarest have a new ‘speedvalve’ on one model Neoair. This looks like a roll top about 20cm wide. Towards the end of the video they say ‘tuck the black inner valve all the way inside’ before rolling it 7 times to close. The camera doesn’t show this ‘inner valve’. Has anyone seen one? It may be key to keeping it airtight.