55.2-59 Sun Visor gasket?

I have both a fiberglass visor that came with my truck when I bought it and a new metal visor from Classic Parts that I bought years ago. I plan to install one of theses soon but I don’t have a gasket for it. I see Classic now sells one but I saw a 57 Suburban on tv today that looks like they used the same welting material sold for rear fenders. Has anyone else used this as a gasket before? Do I need to worry about water with either gasket? Would silicone work to “seal” gasket to the roof? Or should I use something else.
Thanks