Talk with some-one in the Boat builing industry. i had a person tell me about a putty / mastic that when used can not be undone.
That means if glass needs replacing good luck. When i had same problem
with my 09 , pulled window and found no caulking at all on the top .
Cleaned it up caulked all edges with Boat Life. When reinstalling I also
raised the window 3/8ths of an inch in the opening.
So far plenty of rain in the past two years no leaks.