Documenting the problem seems like a good idea. I used some drip edge on my last boat. I could never get the window leak to stop, so I simply diverted the water.
I even tried this stuff called Captain Tolleys Creeping Crack Cure that might work for the tail lights, but on the boat the windows were under the rear deck and walking in deck kept flexing the caulking.
Due to those stressses, only the gutters worked.
The gutters I used were from Essential Products RV & Marine