There is definitely something shorted or a poor connection to or in the radio/camera. It should be disconnected for now. The house battery going dead is likely a separate problem. Your RV service guy, if a pro, should have knowledge and test equipment to quickly find and fix the problems, if not, find an auto electric repair shop with RV systems experience.Meanwhile disconnect your starting battery and re-connect it to drive the rig when needed. Disconnect the house battery until you find the problem in the house battery circuit. Is there a dealer that sells and services your rig, in your area?