I guess I'll add my 2 cents....
If you can get a square, i would recommend it. We teach AFF students to fly a ram air parachute on the ground and they have never flown even an airplane. And since you are on an island, a steerable parachute will greatly help if you ever have to use it.
Also since there is a DZ on Mustang Island, go hang out and talk to the instructors there. I promise for the trade of a flight in the RV, you'll have instructors lining up to help give you all the ground training you'll ever want and most likely a few beers from the fridge after hours.
If you do get a ram air parachute and are willing, I would recommend doing a tandem skydive. Make sure to tell the instructor that you are wanting to learn to fly the parachute. Even though I always get the students (passengers) to fly the parachute, I would spend more time demonstrating and making sure you understood everything you needed to know. Might even pull a little higher to give you more "stick" time if you will.
You mentioned the fear about getting out of it in water, that same recommendation to go visit your local dropzone is good here too. In order to get a B license for skydiving, jumpers are required to do water training. I am sure that the instructor doing a water training would be willing to do a slightly modified training for you. Again this may require hanging out with some meat bombs eating and drinking around a pool for a few hours one evening generally having a good time... Oh the horror
I always suggest pilots take a little time and visit their local DZ for fellowship, we're all aviators and all love to talk about the sky
you'll get a better understand of their SOP (like what altitude they instruct the jumpers NOT to cross the runway below, etc).
If any pilot is ever around the Thomaston, GA (OPN) area. I welcome you to stop in at Skydive Atlanta. I or any or my fellow instructors would happily do all I have suggested above.
Andy White
Just for reference: I'm an Accelerated Free Fall (AFF) Instructor, a Tandem Instructor, Private Pilot, and an owner of a Comanche 250.