Do you already have lodging secured for those three months? If not, I have a private home available. If you are interested, please e-mail be at email@example.com
Regarding the fishing, just pick up a fishing line, hook, and a weight from Chan's Supermarket (under $5 US), pick up some bait from Eloy or Roque Badillo, rent a kayak from one of the several places that do so ($5 - $10 U.S. per hour), and you are on your own - half day fishing trip at your schedule. Other than that, you might try some evening fishing at the Split, or even off the docks.