If you are going to try to be that big and need that many divers, I think it would be very useful to try to develop a quick training protocol. I think an "UW video of a diver collecting balls would be very valuable to someone who is considering doing the work. Obviously it would have to be in unusually clear water, but it would be very instructive i think.
I would do one "run" with the diver collecting balls in clear water. Then another run in the same lake with good visibility, but with the diver's mask COMPLETELY blacked out, so that people can see how an experienced diver functions with zero visibility and also how he might deal with a few obstacles. I think people would be somewhat surprsed at how rapid a diver can move and how gently he works to avoid being injured by broken glass, sharp metal culvert pipes and all kinds of common hazards.
I never wore fins, and was always weighted pretty negative and had a lot of lead very high on the tank so when I was running forward, I was always "falling forward" in a semi-croached position. I also wore a dive skin under the wetsuit, a hood no matter how warm the water was, and socks and neoprene dive boots and big rubber snow boots on the outside and ankle weights over the snow boots and slip on knee pads were essential (indoor volleyball knee pads worked well).
I was the only guy I knew who wore a BC, everyone else just used a backpack. It is not a typical neutral bouyancy, horizontal trim, recreational diving activity. I was so negative that if I ever had to reach the surface in deep water, I could fill the bc completely, swim as hard as possibble upwards with my hands, reach the surface for just a moment to get my bearings and then rapidly sink back to the muck bottom below, because I was always weighted a lot more than the BC could support.
The absolute weirdest thing with GB diving was when you are working in zero visibility and your hand hits under a ball deflecting it upward, spinning in the water column, and somehow you sense the ball, judge your arm sweep speed, adjust for any turbulent cells formed by your arms and then you move your hand back to near where you hit the ball (but not at the same place because the ball also was knocked forward somewhat), rotate the wrist to a palm-up position, and more often then not, the ball would fall a foot or so downward landing directly into your palm in total darkness