I would contact Belize Yacht Club directly to see what their status is. Don't be fooled by the name, it's just a dock with no facilities. I've heard of transient boaters being turned away from there.
I don't know about other docks but the ECP for our pier permit prevents us from having persons living aboard the boats even short-term.
If you plan on staying long term you'll also have to pay a yearly temporary import duty on the boat. I'm not sure what the time limitation is on a cruising permit, probably 90 days.