I had the same problem on my coho, only smaller. It was symmetric so I didn't care about paddling in circles for the rest of my life. I was more worried about the drag it might add to the hull, although I'm not exactly sure how significant the increase in drag will be. I didn't (& still don't) care how the final product will look, so I filled it with thickened epoxy. I used the wood flour supplied in the kit. It's less epoxy & lighter that way. I did it before glassing the hull. there is a darker area where I filled it, but I don't really care. I don't think anybody will notice it untill I'll tell him.

good luck

erez