I’m no expert, but I wouldn’t do it. I think it would compromise the integrity of the ribs. Especially if you intend to use a 15 hp motor on a 12 footer.
Does it even have a drain in the transom? I have an 11 foot Starcraft with no transom drain; it’s only rated for 5 hp!
I used 2 layers of 3/4 exterior grade plywood, screwed and glued with waterproof titebond, sealed with 3 coats of spar urethane. Looks like new after 5 years.
Not so sure that Trex, etc would be good for a transom. It’s heavy and not very rigid.
I put 2 of these seats in my mirrocraft. They’re mounted on pin swivels. I did lower the bench they’re mounted on, so I was sitting at the same height. Also, the pin mounts I used had a 7 degree angle tilting toward the rear. There is also a rearward tilt built into the millennium seats. I...
If you keep the rope start you don’t need much battery. You could run a fish finder and some led lights off one of those little batteries the kayak guys use. Could save a good chunk of weight there.
Not sure who made those for Wards. I have a ‘71 Starcraft 12 footer and it doesn’t look anything like that. Starcraft had a lapstreaked hull, different gunnels, and transom corners with cast-in handles. Shape of hull is also different.