12V LP gas detector
HEREShould have two wires for 12V, ground wire and positive wire.
Some RVs may have a extra wire for operating a gas shut off valve.
Remove old 12V LP detector, should be able to match wire colors.
Then for CO, buy one of the battery powered versions I showed you above, place it anywhere in the RV (doesn't have to be with the LP detector).
The digital ones are nicer to have, on CO if display ever reads above 0 then you should check to make sure your appliances are not malfunctioning.. Although your cook stove will raise that from zero while in use so opening some windows while cooking is advised.
With gas appliances like your fridge, furnace or water heater they are designed to exhaust to the outside, sometimes under the right conditions the wind can push the exhaust back into the RV. Also helpful if you are using a built in or portable generator..