The switch for the outside light is mounted near the entry door, usually underneath an overhead cabinet. The info on the furnace you give sounds strange. The furnace is turned off and on by a switch on the wall mounted thermostat. It works the same as the one in your house. Never heard about a 5 minute gap between off and on. When turning on the furnace for each camping trip, it is best to bleed the propane line. You do this by lighting the burners on your stove top. This way you know the air is purged out of the lines. Same goes for if you use the hot water heater on propane instead of electric, bleed the propane line.
2014 FR Heritage Glen 282RK
2013 F250 HD 6.7L Diesel
Formerly Owned: 1995 22D Fun Chaser & 2901L Classic