Do a search in the forums for Dow Corning 739 and you will find a few discussions. What convinced me was discussions in there about how Dow recommended 739 for this use. Plus the data sheet like you found specifically says bonding boat windows.
You will regret the things you did not do, more than the things you did.
Get out there!
Saco Bay, Maine
2001 Beneteau Oceanis 361