Charlie,

It's very obvious a lot of hard work went into that project, this makes
it even harder to face criticism, but don't lose sight of the fact that
it's constructive (even though it's deteriorating rapidly.) There really
are numerous problems with your installation, and some will inevitably
lead to catastrophic failure and potential loss of life.

Be careful around that thing until you can fix it up. In the least,
install dedicated anchor points set in a sizeable concrete base, shorten
your top mast and get a thrust bearing up there. Put at least 1/3 of
your rotatable mast below the bearing.

This is by no means a complete list, but I think the majority of readers
will agree it's a good place to start.

Rob