Ferrari 512BB

I am slowly pecking away at the 512BB “sera blue”. I really like how this car is coming out except for sealing the windshield. In the past I have used urethane to do the final sealing around trim but I cannot get it to flow nicely. It keeps coming out lumpy. The Ferrari book says to use silicone but I feel that urethane has a more robust grip and will last longer. It is such a kill-joy to be making progress and be stumped on this detail because you have to trim all of the old stuff out and start over, 10-12 hours work?
Yeah