Refrigerator temp

I am betting it's located in a slide?

40 to 44 degrees in the fresh food compartment with outside temps in the 90s sounds pretty good to me.

Check the ventilating fan behind the refrigerator. Add more fans as needed.

Check the insulation at the top and sides of the refrigerator. Add insulation as needed and tape to keep outdoor air away from the refrigerator cabinet.

In central Florida I'm seeing about 35F in the wee hours of the night and 45F in the afternoon. It's been working that way in summer for the past eight years.

1st off.....Model of that Dometic would be helpful

Moving thermistor.....that suggests you do not have 'adjustable temp settings" but an 'auto temp control' model

Unplug thermistor leads from lower circuit board (usually on upper left area of board....2 leads)
Run fridge for 12 hrs w/o thermistor...no temp sensing feedback to thermostat so fridge will cooling continuously.
Food compartment should get very cold provided circuit board is functioning properly and cooling unit is capable of full cooling