Better yet...
Hello,
Instead of a compression tube, consider bushings. This does the same job that tubes do -- recruiting more mast molecules to take the load -- but with less mass up there, and no danger of corroding the tube to the bolt over time (one of my least favorite things).
We use shouldered stainless bushings, and mate them to tangs built with them in mind. On very thin-wall/high-load masts we might add a second, aluminum bushing around the first, and for extreme cases we'll also add a backing plate in the mast.
Note, no matter what you use, cut the bolt thread so that it stops exactly at the tang. That way there's no weakened bolt under the load.
Fair leads,
Brion Toss
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