If a guy wanted to be a real pratt he could point out many unsafe practises on that one flight.
You long-lined the boat, (good on ya BTW! that's the safest thing you could have done) now did you fly from the right or left ?? If from the left, you had someone in the command seat who did not have a license. If from the right, did you stick your head out the window, or take a door off? If you took the door off, and it was a civvy 205 (not ex-mil UH-1) you violated the limitations section of the manual. Read the very first paragraph in Limitations, and you will see it written that flying with the crew doors (pilot's/co-pilots doors) off in an assymetrical condition is prohibited. If you used the window, then ignore the point.
How was the boat driver deemed necessary ?? When flying forest fire ops, no forestry officials are allowed to ride along while we are performing slinging ops (except when bucketing). They are not deemed to be necessary, even though they are trained in slinging ops.
When you dropped the boat driver off, where was the long-line? You didn't mention if you dropped it on the shore or what you did with it. I hope you didn't have it on while you performed the drop off. I shudder to think what it could have gotten snagged on while it was out of sight on the bottom of the river.
You dropped him from 20 feet. You were unable to get any lower? That seems to me to be rather high for a hover exit with someone who is untrained in the operation. While performing hover-exit ops we will not do it if the person has to fall from the aircraft. It's just plain dangerous.