GREAT idea with the expanding foam in the mast... why have I never heard of it before? Think about it: doesn't add any buoyancy, but does the job of keeping water out of mast, without the added wind drag of a float-bob.

The foam is heavier than air, so you might want to check by how much... ;')

Anyway, I don't think that foam (e.g. 'Great Stuff') is corrosive, as it's used in contact with all kinds of metals, incl. aluminum.

Don't know what to tell you about the bolt-rope tracks, but you seem to be very crafty at keeping the old gal lakeworthy!