Jack, I installed the kajak sport skeg without the flanged. I ordered directly from Kajak sport in Finland. You can search this forum on multiple discussions on the pros and cons of the Kajak Sport skeg. There is one builder that cut off the flanges and installed the skeg to sit flush with the inside of the kayak. I was worried that the flange would not be at the correct angle to my hull, which means I would have had to "inlay the flange on 1/4 thick strips or grind down the side of the flanges. When I installed the skeg there was not any instructions. Please pay close attention to the spacer needed during installation. "Inside core is highly recommended to use (core thickness 6,2 mm)"
as noted in the instructions. This will prevent the skeg box compressing during your fiberglass/epoxy lay up. If you have glide problems with the skeg, you can slowly and methodically sand/file down the inside ridges.

During installation I lubed the cable with waterproof bike lube and haven't had any trouble with it for the last two years.

Good Luck