Let air in there
From time to time, you should open the caravan up, perhaps for a few hours on a monthly basis, and that will include the trimmings, such as your rally tent and awnings so that the cabin and all the accessories can air.
“If a caravan is stored under cover, you can keep a window open slightly just to allow a little fresh air to flow to avoid any moisture from being trapped inside. The extra moisture could lead to mildew on cushions or canvas, even in new caravans, and eventually lead to wood rot on older models,” says Brendon Vos, workshop and operations manager at Natal Caravans.