Sea to summit mattress - using a single duvet cover

[IanE]

Hi all - I’ve had a go at finding an answer using search as I appreciate there’s loads on the sea to summit mattress, but I’ve failed .

We find using a single duvet cover as opposed to a fitted sheet ideal as there’s no way I can ruck it up with my interminable turning over during the night. We just have one problem, which is that we haven’t succeeded in effectively securing the cover at its open end. It’s probably just a bit too short. I just wondered if anyone had found the ideal fitting duvet cover - and if so, could they provide a link please?

Thank you!