I hope you have something taking the weight on the front of the boards besides the windshield frame. There is not much holding that on besides the glue and the windshield. You are not supposed to use the windshield to help yourself get in and out because you can damage it and I imagine you could apply a lot more force with a few surfboards and the wind blowing on them while driving.
i dont want to start a flame war but im pretty interested in chucks point. (vampyre, i live in sf, there are a ton of additional costs to a second car that i cant afford. wish i could. want to park, insure, and lend me that rainier?)
i imagine that at 155mph the down force on the windshield has to be a few hundred pounds. strapping something to the windshield is also very different then using it as a handhold when getting out. remember, force = mass x acceleration, so its very different when you pull yourself up. a 150lb guy could easily generate more then 150lbs of force when pulling themselves up. ive seen threads about this damage, but i imagine that is either a defect or has something to do with how fast (force) people are pulling themselves out. not saying its a good idea, just think its a misinterpretation of the physics.
also, surfboards will fly off the car if you dont strap them down. they apply lift. so its not the windshield im worried about, its my 5 point harness mount!