If your windshield leaks BADLY after replacement, no amount of inside or outside injecting of sealant will fix the leak. I HAVE NEVER HEARD OF OR SEEN ANY WINDSHIELD LEAK ATTEMPTED TO BE FIXED FROM THE INSIDE. This is based on 41 years as a RV service tech and I have seen hundreds of windshields replaced or leaks fixed. Small drip leak in heavy water or rain, you can inject black urethane and hope it fixes the leak. IF there is any moisture inside the leak area and you do not get it dry, no amount of sealant will fix the problem. Now, the best way to replace a windshield (as long as the gasket is in good repair AND/or you have a gasket. Some are glued onto the cap with no rubber gasket), you use the Urethane to seal the perimeter of the glass. IF you have a massive leak the only correct fix is to pull the Glass and redo the complete install including a new rubber seal. Patch jobs will never work. Also, you MUST let the sealant/adhesive cure for at least 6 hours before moving the RV. Overnight is best. But, if you move too soon the Urethane will not stay set and you will have leaks. Doug
PS, you want it to leak? USE SILICONE:B