Camp bed + sim... how?

[VolcanionSteamArtillery]

Ive seen this recommended and wondered how it works. How do you stop it falling off? Photos would be much appreciated. Any recommendations for camp beds or sims?

I got some really wide elastic and made two bands to go around the campbed, I then slip the sim under the elastic. To be honest though, I think it would stay put without them, the bottom of the sim and the campbed fabric are quite grippy fabric.

I've just come back from five days away. I did camp bed, fleecy blanket, then SIM then sleeping bag. Worked a treat.

Thank you for the replies. I guess i need to give it a go...