I installed ports in front of the front pylon on my 25 year old H16 and didn't have any trouble at all. I cut the hole with a router and straight 1/4" bit. I sealed the exposed edge with a little epoxy and then installed the ports using a good grade of silicone caulking. I ended up not even installing the screws to hold it in place. That was 5 years ago and it's still as solid as the day it was installed. Here's a photo of the portion of the hull that was removed.