What sleep setup for a 4 year old

I want to start camping with my son. He's 4 now turning 5 in June. What sort of sleep setup should I be looking for. For myself I'm used to a sleeping bag and a thermarese pad but he rolls around a lot in his sleep so I fell like he might just roll off the sleep pad.

We will be camping near the bay area so it's not too cold but I'd like to at least get out in the yard for a night some time in the next month so it will get down to 40.

I was looking at inflatable beds with bumpers to keep him contained but I think that might get too cold.