Hiya Andy
I have learnt the hard way as no one is really around to give you advice and now we have this site its a big advantage..........
Ok Curtains pulled all winter will in the end ROT, (mine did and had to reline them) Blinds pulled down all winter is tension on the springs, (had one blind break as a result) So have come up with the idea of cutting cardboard the size of the windows,except the window in your van that faces north, (thats if you have one)if you dont like to look at the cardboard from the outside,you can always put pitcures on it,as for the damp inside put two or three icecream cartons in the van with about 3/4 inches of salt in it, i also keep all doors including the toilet door open and open all lockers and cuboards inside,Ive had no trouble except faded cardboard,hope this is helpfull,Eddie