My son bought a neat air mattress, you pull the plug and it has kind of a spring inside and inflates itself. When your finished you pull the plug again and just roll it up.
I night fish a lot, I usually last until dawn or so, then crash for a few hours in the back of the XJ, with the hatch open. I'm 6'4", my feet hang out the back a bit. I've got a big plastic tarp I can hang over the hatch and stake to the ground if it rains, I use a lot of Mosquito repellent, learned that one the hard way.
It takes me minutes to set up and take down.
I've also got an elastic pistol belt and a holster that sits right where my belt buckle would be. A compact nine fits in there just fine. I never sleep on my stomach so that isn't an issue. About the same reason I never zip a fart sack closed. You just might have to bail out quick and be ready to fight instantly.
I once pulled over at a rest stop and tried to catch a nap on the bench seat of my pick up. The noise that woke me up was from some fool trying to break into my truck. I cleaned the fog off the inside of the window and showed him the business end of my 12 gauge. I sure am glad I took it out form behind the seat and laid it on the floor before I went to sleep. He got big eyes looking down the barrel of that twelve cylinder bore and decided to move along.

I'm sure glad I didn't have to pull the trigger, it probably would have blown my eardrums out.
I was out hunting with a buddy and his family, he in a VW camper, me and my brother in a VW buggy. My brother and I decided to sleep on the ground. Somebody came into our camp at zero dark thirty and started stealing our gear. My buddy hollers from inside the camper, who's there? He then yells get out of our camp. Somebody says F*** you and the next thing I hear is four pistol shots. There were three of them, two tripped over me and and my brother on the way out of camp, we got a couple of licks in. He didn't even bother to open a window, he just shot through the side of the bus LOL.