If you don't think the tuners are snug enough you can wrap the shaft (B in the pic) with aluminum or copper tape (what you'd use for shielding). It's...
I know that feeling! Those very high frets look like they are getting very flat, before you see anything come off the 13th or 10th (depending on what...
It's done, and your approach should work. It's not a substitute for fret leveling, but it can be helpful when you have a single fret--or just a part...