I use my mast as a ridge pole, supported at three points, bow pulpit, behind the house, and at the transom. This makes the mast very rigid, and I am not worried about potential snow load. With only 2 supports at each end, the mast is flexible, and could potentially be bent by snow load. I can remove my life line stanchions, so a tarp goes pretty much from mast ridge pole to the sides of the boat, making a reasonably steep pitch for snow. If you can't remove the stanchions, you MUST find some way to support a tarp so that snow and perhaps pools of rain water will not push the tarp in and bend your stanchions. Many people make up a framework higher than the stanchions, usually out of PVC pipe and fittings. Don't glue them, so you can disassemble for storage for next year. I also buy heavy duty silver polyethylene tarps from tarpusa.com, because A) I can get heavier material than at the typical big box store blue tarp and B) I can get longer aspect ratio tarps than the more square aspect ratio tarps at the big box stores. (I use a 12x25) Buy yourself some polyester utility cord if you can find some. I have a bunch of 1/4" braided over parallel strand core that was made and sold by a company which used to come to the Atlantic City Boat show every year. I can't remember who they are, but I can see what their business card looked like in my mind's eye - just can't read the words. Darned if I know where I put that card... Anyway, it is a more economical utility cord than a double braid polyester. The polyester is good for chafe resistance on the trailer, and UV resistance. Bungee cords suck for holding on tarps, and the brightly colored polypropylene utility cord you can get at the big box store is absolute crap which will crumble and fall apart from UV exposure within 2 years. Novabraid.com once told me they made a plain white 3/16" polyester utility cord for $0.15/ft but that was 7 years ago. It would probably be a nice rope to use for tarp tiedown if you can't find inexpensive polyester elsewhere. I did a web search and came up with 100' spools of no-name 1/4" polyester rope for $15.00, which is pretty cheap, really.
1/4" Polyester Rope White