For fine filling you can use body filler that comes in a tube. Years back it was called "red lead" There's many of them out there now. It air dries very fast. It's lackquer based. I think Duro and Bondo both sell it. I used it on a Ches. 17 - 5 years ago. It sands super easily. With paint over it you'll have no problems. We still paddle that boat and the finish is perfect. We finished the boat with 1 part interlux boat enamel.