For those of us in Canada that are close to a Princess Auto you can pick up a boat cover for a great price. The one in the pictures is for a 22-24ft boat ($160). I was surprised I could get it over the folded tower, but I thought the pressure on the hing points might tear it, so I made the cuts for the tower. I still need to make velcro strips and webbing to rip-stop the cuts. As well, I was going to add a 1" strap and ratchet to the circumference. The sewing can be done on a home machine with thicker polyester or nylon thread. Even including the ratchet, the total price will be less than $200.
It was a lot more sewing than I expected. With the cover being so low in the front, I may still have to shorten the around the boat strap in the front a few inches. Also, I may need to put a few more darts to bring in the material. However, with the straps to the trailer, it holds it in place very well when driving.