Refrigerator Temp

The other day when it was in the 90+ deg. range outside the Refrigerator Temp. could only get down to 48 50 deg., but over night the temp when the outside temp fell it went back to 34 deg. I read in one of the treads on this form that a absorption type frig can only go 40deg below ambient(outside temp). if this is true it would explain the temp swing.

plugged in, then propane same result

What you're seeing is normal per my experience. Overall about 40F delta from outside ambient. There is a lag as it warms up outside and a longer lag as the fridge tries to cool down after a hot afternoon. Propane or shore power about the same, 12V battery not so good. Opening the door is really bad. 

My post was not based on theoretical thermoelectric or absorption technology. It was based on my observation of the Dometic 8501 in my RP172. It reflects not only the technology, but the particular application including unit capacity and box insulation. I wish I could have maintained 40F (4C) with ambient at 95F, but I couldn't. In testing I did use a wireless thermometer to avoid unnecessary door opening, but the fridge was in use. The larger Dometic in my Camplite works better but I attribute that to better design and construction. 

The thermostat and fans sound like a good idea. Can you show some pictures or explain a bit more. I'm not sure why you would need another thermostat?