Your other option is to shrinkwrap to the toe rail and leave the stanchions / pulpits outside the wrapping. That would be a pain to do and leave multiple holes through the wrap.
I had the same stanchion bending problem with the earlier canvas winter cover on my boat, so I replaced it with a new one that runs from the boom to overlap the toe rail. Having the cover not go over the stanchions also improves the slope of the "roof" to more easily shed the snow.
With my C-30, I didn't cover the entire boat for the winter. I just covered teh companopnway and the main hatch. six years later when I bought a new C-320, I had a cover made as described above. Worked beautifully for 5 years (until I sold the boat, and has worked beautifully for the next owner since), and this is the second winter on te new cover on my C-380 that replaced the previous stanchion bending cover (purchased by the PO).
I wouldn't put anything over the stanchions for the winter without adding something to prevent them bending in.
Steve
Alchemist C-30T #4764
Alchemist C-320 #909
Alchemist C-380T #71