My experience with DC on a number of fridges over the years is that it doesn't work as well as AC.
I have heard of some people placing an invertor in the tow vehicle to run the fridge on AC while towing. They usually don't draw but 200 watts or so max so it doesn't need a very large invertor.
Food for thought.
One of the best things we ever bought for camping is an ARB 12V compressor "ice chest". That thing is amazing and it pretty much stays in our FJ Cruiser. It draws about 5 amps running but doesn't run much.
The wife even uses it when grocery shopping, doesn't have to worry about rushing home with cold or frozen food. It will even go down to 0 deg.
When I built my own interior in my Four Wheel camper I installed a NovaKool marine 12v fridge. Best thing about 12V compressor fridges is there is no concern whatsoever about parking level.
One thing about the RM8501 is if a replacement is needed- it doesn't have the same dimensions as any other fridge Dometic sells in the US. Yesterday I emailed Dometic Customer Support asking for a manual on the 8501 and also asking why it doesn't seem to be sold in the US. They sent me the manual but chose not to comment on the US part