How bad a dealer's service dept can be

Still no solution.  I've run tests, rechecked the orifice, tried a different propane tank, and it still won't cool in propane mode.  The flame looks good.  I have to verify but I think it starts off cooling and then stops.  Cools great in AC or DC mode.

The insulation is apparently pretty good in the ARB.  A couple of times it has accidently come unplugged and when discovered hours later the temp has barely risen.
I leave it in the tow vehicle and plug in an adapter to the 7 way on the trailer when parked overnight to use the camper batteries to power it.

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

The Dometic RM8501 is what is in my rpod also.  Says made in Germany.    The odd thing is that particular unit seems to be non-existant in the US, except for maybe an OEM item.
Apparently Airstream is using them too- in fact one of their owners is having the same problem techntrek is having...
So what is up with FR using a fridge that may have service and parts issues?

We had/have a recurring problem on the LP as well.  It was the igniter bit falling over and touching the other part.  I'm not sure what it's called.  Anyways, the fridge just would not ignite because there was no spark so we kept on hearing a clicking sound for a bit and then got the error.