Get one of these next time they are on sale. Try it out at home with your stick house fridge to be sure it will handle the surges--it has enough watts to run it. (I have run 120v fridges on MSW inverter--you do not need PSW for that) This has 700w plus surge. Reports on this forum say that you need at least a 600w inverter with a res fridge in an RV.
If it does not do it, they accept returns, so worth a try IMO.
Then carry it with you when you RV all the time anyway. Could be very handy for other things that happen!
You could run the fridge with it going down the road and recharge it on shore power when you get there each day. At Walmart overnight, I don't know how long this would go. You can clamp it to your house battery to get extra time. Going down the road following that night until you get 120 again would need some help from alternator/7-pin 12v.
https://www.canadiantire.ca/en/pdp/motomaster-eliminator-powerbox-2000-0112028p.html#srp
