Hi Shorefisher, I'm in Sanibel a bit later than you. 7-12th June.
In North Captiva the week before.
Hope you have a good trip and great fishing.
I don't know what other people do, but I usually use 1/2 to 1 oz sinker on the bottom of the sabiki depending on the waves. sometime I spike the hooks with a tiny piece of squid. The downside of the squid is that it sometimes produces too many catfish bites.
As for the balloon, I thought about that too, but I'm thinking the rubberband is not going to break easily enough. I was thinking perhaps sewing thread. The Sanibel sandbars have some pretty sharp shells. I like the balloon thing and will try it if I can figure out how to get rid of the balloon.
One technic I learned is cutting the rubber band then tying a Uni knot with it around the line. Then you could set it where ever you want, goes through the guides fine and is easy to take off. Then have the ballon on a slider rig, so it can only slide as far as the rubber band.