Scott,
Foam? Well that's a new idea. Did it work in keeping the mast wiring Quiet? Don Casey in This Old Boat recomended/suggested using aluminum pop-rivets to fasten lengths of PVC pipe to the inside of the mast to form a wire chase. Something needs to be done to minimize that annoying 'ding' at anchor.
Why is it you don't want to pull the masthead off? Seem like an ideal time to do it and it would give you a better look inside the big stick. But to answere your questions-no, not yet, undecided, undecided.