(UPDATE: video in comment) pictures of me in the vacbed this afternoon

What's stopping you from getting one? I'd recommend against a zipper because it's not truly airtight. Get one with some extra latex at the top and roll it up from the inside, that should work better.

How do you roll it up from the inside? I've tried multiple times to do that using plastic bags with very little success.

You need 2 pieces of tube on the inside, one that fits in the frame that you can use as support for the 'sleeve' when you pull the excess from the entry into the bag. Then a shorter one where you roll the sleeve towards the top of the frame where you also have the first piece. I can imagine this being harder with plastic than with latex.

I don’t see how you use the first tube?

I used to just roll the excess of my with my hand the put 8 cloth pin on it. But this might be why it was not airtight…

But since my vacbed is now ripped, I’ll try this with my next one (and chlorinate it for less storage hassle)