Easiest way to handle this is to unhook all the detectors and replace with HOME Depot residential ones that run on AA batteries.
My propane alarm would go off for no reason and a real PITA! especially at night or while cooking. Neighbors loved it too. I also replaced my CO detector and smoke detector combo the same way.
You can remove the built in detector and place the surface mount over the hole if you want.
Then just keep some AA batteries in the camper when replacement time comes.