Mr. Heater Big Buddy Indoor/Outdoor Propane Heater

I dont know offhand the specs of the furnace in our camper, but our pup is a little smaller. Nonetheless, there is a carbon monoxide detector on the inside. Yours should have one too. You can locate it in the manual (or online) and test it similar to a standard smoke detector. You could buy an after market one as well, but I'll bet my dollar that you already have one.