How do you make sure your bedding doesn't go over baby's head and suffocate it?

Background: None of my kids have co-slept, apart from when I used to occasionally feed DS1 in bed in the early morning in the hope that he would then sleep in a bit more. But, we are going camping in about 6 weeks and DS2 isn't a great sleeper. Obviously I can't have him waking up everyone in our tent and possibly the whole caravan park, so I need a few strategies up my sleeve for if he doesn't settle. But the thing that has always worried me whenever I have a baby in bed with me is that my doona will end up over their head and suffocate them. So I make sure the doona is well down, which means I get cold and don't sleep well.

Any suggestions please?