More info here.
http://rvroadtrip.us/library/digital_thermostat.php
And here.
http://www.modmyrv.com/2008/07/14/rv-digital-thermostat
These are just some of the links you will find if you search the internet for "Converting camper thermostats to digital.
Also for future reference you should tell us what kind of camper you have, year, make and model. And in this case what kind of original thermostats
do you have.
I added a switch on the side for the fan Hi/lo.
Using the very basic Digital Thermostat keeps things simple.
Sudsy