Planers , Erberspachers , and the Chinese copies all come with base plates that should be fitted level with the floor surface , therefore meaning that exhaust out , air in and diesel in will in effect be outside the caravan meaning no chance of CO2 or any nasties coming in , as long as it’s done by a person with sense it will be a doddle , the unit will perform better inside and vented properly , also a 5 kw version is by far the best option for a caravan type space, also running any of the versions out there best to be run at full power for 10 minutes before switch off , this reduces the coking up greatly .
It’s times like this when I would give my time to help !