Well, the job is done, but nothing ever seems to go smooth.
I removed the old port light yesterday. I found that the PO had not done me any favors.
1) It has 10 fasteners. There were four different types installed, including four bolts. It is supposed to be in with 10 stainless wood screws,1/2 inch, oval head. Three of the screws were not stainless, and of course all three had rusted heads. Insert phillips screw driver, turn, and instant head strip. I used a Dremel cut off wheel to cut in slots. I was able to back one of the three out. On the other two the head broke in half as soon as I turned the screw driver. I had to grind the heads off with the Dremel, then used wire and a putty knife to cut the sealant, and back the port light out over the remaining two studs. The studs were removed with pliers
2) There were two different sealants. It looked like old silicone clear had yellowed and was caked onto the original sealant. It took a while to clean it all up.
The pictures show the old port light, with the broken dog latch on the right - the reason I removed it. The second picture shows the assortment of screws. It should of been 10 of the items on the left in the picture.
The new port light went in just fine with Dow sealant. Many thanks to Stu for posting a picture of the rig to compress it and keep it in place while the sealant hardens up. I make one up while it rained last weekend and it worked great.
Before applying sealant, I put it in place and attached painters tape around the port light and edges in the interior and exterior. After adding the sealant and pushing the port light in place, I compressed it with Stu's tool, put in the screws, and waited 90 minutes. At that time I just pealed away the tape and excess sealant that squeezed out came right off, no mess and a clean line.