My 10-year-old Dometic 3-way has intermittent problems (it won't cool enough for safe food in very hot weather and the igniter sometimes does its job and sometimes not). Sometimes the fridge works fine on both propane shore power. I don't feel like replacing it right now.
Plan B when it lets me down is to use it like an ice chest. At home, I have a large collection of refreezable blue ice blocks which can be used. In case of failure during a trip, bags of ice from the store.
For hot-weather trips, when I can pretty much figure no cooling from the Dometic 3-way, I have recently purchased a small portable 12V Dometic CDF-11. This worked very well on a recent trip in 105 degree weather. It cost about $300, fits between the cab seats, and runs off either the truck's 12V or the coach batteries.