Over many years of caravan ownership I've only had a cover for one, the cover was very well pit together, but quite difficult to fit, particularly in anything other than calm conditions.
All the projects on the caravan, ends of roof sealing trips,etc had to be padded before fitting and the Staus antenna either romoved or specified such that it could be included in the cover.
The next problem was the windows. However good the fit the cover will move slightly in anything above moderate wind and can abrade the relatively soft ( compared to glass) plastic windows, particularly at the front.
The problem gets worse with use as inevitably dust etc will get into the cover during the process of fitting and removing.
With all this and incrasing age with decreasing mobility the cover went with the caravan when sold, and I have never bought another,
You could consider a cover for the roof only, but this has the same fitting problem for the antenna and unless bungeeded down very securely will catch the wind too.
I would suggest using a good overwintering liquid which will protect from bird droppings etc, is much easier and cheaper. Unless you sell a cover with the van you may find it does not have much after market value.
This will probably provoke happy cover owners to disagree, but at least you may get more opinions.