I've used the same set up on my Tartan 34 and now my Hunter 420. I
have a 1/2 inch line preventer using a block and becket with shackle
to attach to the boom and a fiddle with camcleat and shackle for a
stanchion base. Currently I leave both shackles attached to the boom
where the vang is attached and a shirt piece of shock cord with hooks
to hold the three line loops of the preventer to the mast base. It
lies snug against the vang and to use it I simply free the line from
the shock cord unhook the camcleat end from the boom and lead it to a
stanchion base. The camcleat makes any fastening or leading to
another fixture unnecessary.