Heat pads will not protect your whole water system from freezing and experience significant damage. You will need to keep and assure that your camper does not fall below 32 deg at any time, and that takes running the furnace or providing supplemental heat to the units including the water lines and tanks.
It takes a lot of heat to do this, and you have to make sure the heat is circulated throughout the unit.
2007 Chevy 2500HD Classic LBZ Duramax/Allison (Stock)
2005 Bigfoot 1500C8.2 AWESOME