My thoughts on this are quite simple, there is no substitute for correct heating and ventilation.
Using a hob for heat gives us two potential problems, Any fault on the burners that effects efficient combustion will result in producing Carbon Monoxide. Even when tested flame picture is realistically all that can be observed. Food detritus , spilt liquids can soon affect burning efficiency,
To give an idea only 400 parts per million of CO can produce risk of life after 3 hours exposure. It does not take a lot of CO to kill people. Naturally a cooker you wouldn't use for this period but the OP is talking about heating. in a small space and I often wonder how many self builds particularly are adequately ventilated.
Even if things are working correctly, correct combustion produces Carbon dioxide co2 and water vapour. The latter is condensation as the temperature drops, the atmosphere becomes "damp" and uncomfortable.
A lot of people invest faith in carbon monoxide detectors and whilst never a bad idea, Better to have than not have , It seems to me people see them as the guardian angel and they are NOT
By nature of motor home size and the size of the living space correct location is extremely difficult and often a compromise. The type of detector for info purposes should comply with EN 50291 and installation should comply with EN 50292 ( the latter is a guide for selection siting and maintenance )
Considerations where not to site
1) Where they can be obstructed by furniture blinds and curtains
2)Where it located in an area subject to draughts of fresh air , so doors windows and vents
3)Above or adjacent to sources of heat
4)Where dirt or dust can or could block the sensors
5) In damp or humid areas.
Hopefully I have demonstrated and readers can see motorhomes are not conducive to correct installation by their nature.
My last point is I get the impression people see them as foolproof , and a guaranteed insurance .I am suggesting they aren't !Of course they are useful but please don't think they are a guaranteed Get out of Jail card
Channa