Yeah, Duct tape has it's places, even different places for the "good and sticky" 3-M stuff as opposed to the el-cheapo Asian/Chinese stuff (which seems to be a bit more porous, but stretches more). The guys Chris and I have pit-crewed for had some of each for different applications.
I have to credit "East Coast Bruce" with the blue painter's tape idea. When we were at Carlisle a couple of years back we blasted off for the Eastern Motorsports Museum in a slight drizzle that quickly turned into a DOWNPOUR. He had already put on the blue tape the day before for the ride in (it was rainy all weekend) and at least his windshield didn't leak. Had small ponds behind the seats which he was continually bailing, but their knees stayed sorta dry...
I had some decent, tubular weather seal between my header and windshield frame which didn't leak, but I lost it when I pulled it out to install a center latch last Winter. I plan on getting some more shortly when I replace my CMC POS windshield so, hopefully, that'll be cured again, too.
gn