Fly fishing (as seen on TV) uses the weight of the line itself to enable the cast. They even have a bit of weight bias so that the line is heavier per inch near the cast end than in the middle.

Fly lines are made as either floating (most of them) or sinking so as to have options on how to fish.

I think the casting bubble and some flies is the way to go for the situation described. Oh, and some fly floatant to ensure the fly really does float when it gets to the water on the cast. Unless of course you are fishing with a subsurface fly....