When we had 4 at home kids, and a tight budget, we traveled with a popup with a 12/120 volt refrigerator. I wired a 12 volt line from the car to the refrigerator and ran the fridge while driving. As long as I unplugged it when we stopped, It worked well for 5 two week vacations. If I forgot to unplug when we stopped, the fridge would kill the car battery. I did not know about battery isolators at the time. I would check with a volt meter to see if the alternator can keep up with demand while running the engine and with the fridge running. My Caprice Classic had a high output alternator and it kept up.
