most of the new pwc 2 strokes are efi and run clean.my outboard runs a little rich but the smoke you see is unburned hydrocarbons not co.those big boats with camshafts and holley carbs with blown power valves throw out a lot more smog.i think the channel should be run 1 way a couple of weekends and the air sampled .but the fact that government is involved means that no easy common sense based solution will be found.maybe some pull ropes in the water running on electric motors so you can shut your motor off.