we no longer use a cover as we caravan full time, I have used the specialised accessories one in the past and it was excellent,however it got to the point where we were using the van more and got sick of removing it ,washing the van when you get back and then refitting, that got me on to FENWICKS OVER WINTERING FLUID, wash the van rinse off etc then mix up and apply the over wintering fluid either by sponge or better still a garden sprayer, this leaves like a very thin waxy like layer coating on the van and is easily washed off again using the caravan cleaner at the beginning of the season. bonus here is the caravan can still be used at any time as the coating is bearly visible, I will still be appling a coat before winter to help keep the van clean and free from algea etc even though we are in it all the time, it's not a bad idea to leave a coating on the roof all the time to protect against tree sap, bird turd etc..... Mark