Could fill it with bondo, or would that be a bit too heavy?
Looks really good, I might do this myself - let me know when you find out how to fill those holesthey look really nasty atm, but if you can get a good solution to the holes then im all over it.
Plastic welding is the solution. Using the piece you cut off, weld it back over the holes with this.http://cgi.ebay.com.au/PLASTIC-WELDER-KIT-FOR-CANOE-KAYAK--ALL-PLASTIC-REPAIRS_W0QQitemZ180315776813QQcmdZViewItemQQimsxZ20081223?IMSfp=TL081223123001r5359Second option would be to cut it from the inside somehow with a dremel or grinder, removing all the unwanted areas, then bend it over the holes and finishing it off nicely with a file. Then you will need black silicone, and sparingly seal it up. Cure time is 24 to 48 hrs.