A simple tall A-frame will do it! I just made one for my 16' skiff, using 2x4s as the vertical posts, about 4' higher than the gunnels. A 10' long 2x3 spans the 2 main vertical posts, then I put strapping out to fore and aft, screwed to that beam for a good foot.
Get some old/scrap remnant carpet and cover the wear points. I also put strapping as supports down from the main beam to 3" over the gunnels, where the vertical supports are. I'll try to post pictures.
But for years, on boats up to my toona boat (complete w/ tuna tower), I'd tarp them in this way - steep A-frame. The steep A-frame sheds snow and ice perfectly! Others here north of Boston were paying $10-$12 per foot for shrink wrap and I'd build a frame and buy a tarp for $100+ and get 3-4 seasons out of it before something needed repair or replacement.
Stay tuned for photos ... Oh, this year I bought a white tarp and it is awesome! It is bright underneath anytime there is light out, as I intend to do some more rigging before it gets TOO cold out. I had to tarp it now so the boat doesn't fill with leaves ...