I installed a digital programmable thermostat and just set the clock to raise the temperature when I get up. Note - not all thermostats will work on 12V dc systems. What you do is pick one you like and before you pay for it, flip it over and call the manufacturer's tech phone number on the back of the package. Let them know you are installing it in an RV (dont say truck camper - that will confuse them ) and tell them it is a 12 volt system.
Also tell them if you are only controlling just the heat or heat and A/C