Actually, I think I finally nailed it. Gonna let it sit a little longer and be a perfectionist about it, but a file worked a lit better than a razor. Smoothed it out further at the hole and so far for a few minutes it's sat and not a drop. Looking a lot harder at it I could see right at one of the seams because of the offset of incline and the surface not being precisely flush, I could see the seal had a warped sort of look sitting against the edge. So a combo of filing down to perfection, plus this time around after further digging I caught some comments about the final 1/4 turn at the spigot's side to ensure proper snugness without overdoing it, and yup! That seems to be the key. If I go out to my kitchen in 20 minutes and still see a few drops then I'm just going to default to figuring I need to do a better job of filing and smoothing over the outer edge of the hole.
Definitely looking forward to this haha. Got this kit for my b-day with the Bewitched amber ale brew and I'm finally throwing this all together this weekend to get going.