I have a Sony color cam so not sure I can help much on the Voyager. As previously noted, you may have to remove the top of the dash and check connections at the monitor. If it goes beyond that and you want to talk to an expert on RV cams, I can recommend Tim at RVcams.com.
As to the water heater, I also have the LP/Electric model and had the problem you described. The electric circuit has two switches....one in the coach as you noted and another on the back of the water heater. It is a re-settable switch. In my coach (others have reported the same problem), the switch on the water heater is not sturdy and will easily trip, shutting off power to the heating element. That switch is really not needed since you can turn the element on/off from inside the coach. I removed the switch on my water heater and bypassed it, and have had no further problems. Also, there is a circuit breaker dedicated to the water heater so you will still have that protection.
'07 Country Coach Allure 470 Siskiyou Summit #31578, Cummins ISL 425; 2014 Ford F150 toad; Air Force One Toad Brake.
Glen Allen, VA; Smith Mountain Lake, VA.