is a link to my thermostat upgrades.
I used a residential model as they are cheaper than the Coleman's (I had two to swap), and I also wanted one that was back lit for easier operation at night.
Search WM, HD, Lowes and Amazon for the cheapest one you can find. Painting them black and adding the switch for a two speed fan is optional, there isn't much difference on RV A/C units so some people just wire them for high.
If you use a Honeywell model the wiring should be the same as shown in my link.