Mid-Island Marine rents boats, or at least they did two years ago.
If you really want to go with a good guide, try Mike Reher, the husband of Joyce Rehr who does the FishWire Reports for that area. http://www2.reel-time.com/fishwire/fla-gulf/update.htm The report will also give you a great idea of what's going on and updates on Friday a.m.
I've got a couple of maps up on my site at http://www.geocities.com/Baja/3297/ under the access maps tab which will give you a few good areas to think about fishing. Don't neglect to night fish under the docklights for snook if you can get out. Also, wade fishing at Blind Pass and along the causeway for redfish is good.
Another top guide is Doug Fisher, out of captiva. He's known as one of the top tarpon guys there. He used to fish martha's vineyard in the 70's and was a good friend of spider andresen's.
For other information, try lehr's, a reel-time advertiser. They can give you more recent info on where to fish, what to use, etc. They've also got licenses.
http://www2.reel-time.com/sponsor/Lehrs/Tackle.htm