Going through a similar problem with a Dometic RM2333 three-way. 12v element on the road is quite inadequate, even though I have revamped the baffling to make it close to what Dometic requires. The changes helped, except that the air flow tends to blow out the flame when running on propane
even more frequently than before. So, no propane
use while on the road. I doubt that there is much I can do to keep the flame going reliably.
After changing the wiring for the 12v I have just about given up on that idea, besides the 12v element is only 125 watts versus 175 on AC.
I'm about to install a dedicated 400w inverter to run the frig on AC while on the road. The Odyssey has a 115 Amp alternator and I use two Group 31 batteries in the trailer. I may have to double check the wiring gauges from the alternator to the trailer batteries to determine if they are adequate.
I'm hoping that the AC operation will do the trick without causing undue electrical
drain on the batteries. Arriving at a boondock site with depleted batteries is not going to work either.