I keep my boat on my property but can not fit it into Garage.
So I used to use PVC cover which was cheap enough and I can replace it every year. It is not breathable but I always tray to keep air flow using this cover.
Looking at internet I have found "cover for VAN"
Made in Poland, breathable, some membrane and cheap (60-70 GBP)
It was in some material box, very light.
Easy to put on boat:
Will check this Autumn / Winter how it works
For winter storage I will put PVC pipe between A-Frame and console