Hi Bob,
The duty cycle on the fridge is 2:3. (i.e. 40 minutes on and 20 minutes off), and it draws 325 watts on electric. To test to see if a breaker will "blow" if using a slow cooker--move the fridge to electric.
Probably the condensation drain tube for the fridge is allowing outside air into the fridge. It can make a difference of about 6 C.
The device I use as a slow cooker draws about 300 watts.
I'd recommend a second shore power cord to you. Use it to run another heater. Your propane savings will pay for the cord and heater in short order. I prefer oil filled as they have a surface temperature of only 85 C. They also can be turned off for short periods of time and will "coast" continuing to warm an area.
I never trust the "name plate" wattage. I've only found one out of items I've checked where the wattage was accurate.
