This is why we have two battery operated Carbon Monoxide detectors in all of our bedrooms.
RVer Dies Sleeping in RV camper - RV Tip of the Day (http://rvtipoftheday.com/general-tips/rver-dies-carbon-monoxide-rv-camper)
Ours have digital display and are on opposite walls. Cost is affordable at about $40 each. We think that this is important enough to have a redundant backup in case one unit decides to fail. Just don't want to disappoint family and friends by us waking up dead.
Bedroom location is important because we would not have any wake-able indication of CO.
I am not a fan of diverse combined detectors like smoke & CO. But all of our smoke detectors are ionization & photoelectric combination units and we have these wherever there is hidden major wiring, in addition to normal ceiling locations in each room.
I have three installed. One in the original location, one over the dashboard, and one in the bedroom.
Also keep in mind, carbon monoxide, propane, and smoke detectors all have a finite lifespan. The former should be replaced every 5-7 years, the latter every 5-10.
Said a different way, if you have a 2011 or older coach, check the back of your detectors - they should have manufacturing date stamps on them. If you have owned your coach (of any age) more than 7 years (2009) and have not replaced your detectors, do so now.
Thanks for the reminder. I just ordered one for the bedroom.