The kit recommends painting thin CA over the fins for strength. On my Lance build, which I still haven't finished because of multiple problems, the fins warped when applying the CA. I thought I would apply the CA first before sanding to see what would happen. I clamped the balsa (not what was included in the kit but 1/8" thick) between two pieces of wax paper, applied some CA, and spread it out with a piece of thin cardboard about one inch in from the edge.
I flipped the balsa over, applied clamps and repeated process, but this time went in two inches. Flipped again etc. and ended up with an about three inch square piece of saturated balsa. It was unwarped, so far so good. I cut an untreated balsa section the same size and weighed them, a 1.1 gram difference.
It is even smaller than the fin, so a fin coated would be more. It adds a lot of strength against the grain, but hard to tell short of breaking them with the grain. With that dowel on the end, I'm not sure the fins need that extra strength with the TTW construction. However, if it forms a more defined taper to the airfoil when I sand, it might be worth it. Well, except for one fact, I used about .3-.4 ounces of CA to coat just that one piece of balsa, very expensive real estate if it were laying on the ground. It's time to go to Michael's, and pick up some basswood. I will do some comparison measurements and tests, and then try to decide what works best.
A trip to Michael's might take a couple days, so I think the next step will be the tip of the nose cone. I'm going to give Bradycros'es JB Weld method a shot, even though I've never used the stuff before. The rocket built stock requires an ounce of nose weight, so a nice strong tip will be a plus, and will still need plenty of weight. Here's his Logo rocket thread with the how-to.
https://www.rocketryforum.com/showthread.php?t=10709&page=2 It starts on post #54.