We reckon our Dometic fridge runs better now on 12 volts than propane.
We installed a 280watt 12 volt element but wound the 12 volt converter up to around 14.5 volts to get about 13.7 volts at the element so it would produce 325 watts.
Suggest measure the voltage at element and amps its drawing to check the element is producing 325 watts as per Dometics specs.
Have a listen to this:
We have also installed computer fans in the back to aid cooling, we felt a fan inside the fridge was little benefit.
Inside directly above the fridge that void we measured at 55 C.
Still to do: Try to cut the panel beside the left top of the fridge then try and remove the thin ply above the front of the fridge, then
1/ Install a baffle to prevent hot air from the furnance getting there and try and push more insulation down the sides and top.