Hello Trevor.
You have a problem with condensation.
Condensation is the result of warm air absorbing moisture from thinks like us breathing, any open flame such as the gas hob or oven or heating pots or kettles which boil and produce steam. If this warm air is cooled such as coming into contact with a cooler surface, the cooler air can't carry as much moisture so it deposits it as condensation.
You can't stop this, but you can minimise its effects by increasing ventilation.
Now I don't know the construction of your awning , but to make an airbeam airtight, it must be impervious. If the whole awning is manufactured from the same material then firstly it wont allow air to through it, and secondly it won't allow any moisture to wick through it (under capillary action) to disperse any condensation that does form.
As I wrote, ventilation is the solution.
Don't forget that typical sources of moisture are the air we breath out, and in some cases the fridge exhaust vent exits inside the awning. Also when you open the caravan door, the warm moist air will begin to move in to the awning, so things like the gas used on the hob, and any boiling such as kettles or cooking pots will load the air with moisture. As the awning is outside it will be cooler than the inside of the caravan and will make an ideal surface to cool moisture laden air to condense excess moisture.