Dan,
I to have ideas of going bigger. A 4-5 foot sycle bar would be ideal. Not sure where to find one of these. Maybe a tractor junkyard or a small engine repair shop. They usually have stuff laying around like that. No ofense to any small engine repair guys out there. Also, about the ability to catch and pick up the weeds as they are cut. Great idea! I was thinking along the lines of a conveyer belt system that has a screen for the belt. The conveyer belt is as wide as the cutters in front of it. As the weeds are cut the belt screen picks up the weed and allows the water to pass through as the weeds are lifted up at an angle. You've seen or possible used one of those screens on a pole that scoop up the bugs and leaves from swimming pools? Similar priciple. The weeds are lifted and rolled off the end of the conveyer system into a dumpster bin. This is still just an idea with no real prototype.
Have any ideas where I can find a sycle bar 4-5 foot long?

Have a day that you truly deserve!