Cow bell at one big toe should let you know when to pull you feet back in if the monster under the jeep wants to bike the feet.
I only once even consider sleeping in my CJ5, then quickly dismissed the idea. However, I have on many occasions slept under it.
After several pages (again) of shaking my head at folks trying to make the impractical work...
How about just getting a cheap, easy, quick to set up dome, or similar, tent and not worrying about sleeping in a vehicle that was never intended for it?...If it works for homeless people, it will work for you.
Once an easy to use tent is in hand just man/woman up and use it... forget about; crawlies, boogymen, mountain lions, bears (unless you are in Alaska) and just go to sleep (note; an appropriate sleeping bag and pad helps a lot!).
Enjoy!
I shake my head at a lot of the posts as well and I've decided to keep my mouth shut about a lot of them. People already think I am a cranky old Phart. They are right.
I grew up in the days when you went out for an adventure you carried everything on your back for a week out there.
I can pack for a several day trip in the winter for 2 people and can still see out of the back of my 3B.
My motorhome is a bit different. I admit I have a coffee grinder and a microwave in it.
Happy Joe live your life as you wish to.