Since the LEFT wing tip was already in the cradle, I decided to do this tip in the cradle, as others have suggested. Although I'm just getting started, I think it is indeed better to do this in the cradle.
Aligned the aileron as required, then started fitting and cutting the edges of the wing tip. I did a better, more careful job on this one.
Tomorrow I will sand the cuts and drill the holes.
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I actualy did one other thing tonight. When cutting the trailing edge of the wing tip, it cut far enough that some of the trailing edge disconnected the top and bottom skins. So I put some West Systems epoxy in there and clamped it.