No sanding that I recall. Probably would help with a very course sand paper and then clean thoroughly afterwards. The West Marine kit is expensive but it's one of the best of not the best available to the public.
I had a gash where the hull was separating. About 3-4" long. I made a batch of "peanut butter" which is silica powder mixed with the epoxy resin as a filler and then overload it with fine woven glass in 3 layers. Then came back with a generous top coat and I'll be darned if it was not the strongest part of the boat afterwards. I drove that boat like I stole it on rough water and it's still going strong today. I just saw it yesterday for that matter. The new owner was taking it fishing. That's been almost 2yrs now. I think....maybe a year. I have pics but for what you're doing, it's way overkill.
With West Marine, you can cut a hole in the boat, glass it, and then gel coat it. If it's going to see a it of Sun, you need gel coat to seal it from UV which will dry it out and yellow over time. Again. ...this is for a big boat. For a canoe, the repair cost may warrant a new one compared to the West Marine system. Easy $200 for materials. Maybe more. Tulsa has the closest West Marine but you can ship it too. Just not express mail because it's a hazardous material.
Call Ozark Trading Company out in Pea Ridge and see if they repair or would make a trade for a comparable canoe. They have lots of stock. Just something to explore before plunging into fiberglass repair. It's actually quite simple but the supplies......that's where the cost is. And why bass boats cost so much.