Aluminum is soft. A sandpaper flapper wheel, scotchbrite, or roloc disc will make quick work. Try for a 1:4 ratio... for every 1 mm down, blend 4 over.
You should also inspect the tire bead for embedded rust and old sealant, if you are using a used tire. These can be gingerly touched up with sandpaper themselves. There isn't much rubber there, but if you shave a tiny bit off you might get down to softer rubber.
That said my go-to is the Xtra Seal they sell at every FLAPS.