I would just leave things as they are.
For one thing, I don't think the fridges will fit through the doors on the campers.
For another thing, you run the risk of damaging one or BOTH fridges in the transplant process, and having nothing to show for it at the end.
Operationally, don't fear the propane!!!
The fridge is far and away more efficient on propane, and it's as safe as any other method of powering the fridge.
Lots of people seem to have an irrational fear of propane from watching too many movies. Believe me, a half-dozen things would have to go wrong all at once for a Michael Bay explosion to occur. If you do basic maintenance, four of those six things will *NEVER* happen.
On 12V you're burning up your alternator and wiring harness. In fact, I disconnected the 12V on mine and reused that wiring for a lighter socket for charging my cell phone inside the camper. 12V is just ridiculous.
It's *NOT* expensive. The fridge uses very little propane. In 8 weekend outings, all firing the fridge on Friday afternoon and running continuously through Sunday, I went through 7lbs of propane, *WITH* the water heater running 1-2 times daily, and some furnace use at the end of the season!!!