We have looked long and hard and found that this just doesn't exist, so perhaps someone else has had better luck. In many stores the collapsing part is the issue that confuses people, it needs to be semi rigid to fit into the bag sizing boxes. We never had storage issues on our boats, most boats have "long term" storage under the bunks. But if you store under the bunks use Damp Rid or you will get mildew.

Backpacks are as close as we have gotten.