I'm not familiar with your River but I would guess all commercial vessels monitor Channel 16 and 13. Channel 16 is of course the Coast Guard emergency Channel but it's also a calling channel for all vessels and I have seen it streamed on apps.
You might want to do some research and find just what frequencies are used besides Channel 13. You might look at channel 12, 13, 14. Just search the whole Marine band and see what is actively used for the different barge companies and Maritime control.
As far as Coast Guard I don't think you would have any problem doing 16 + 22. I would avoid 21, 23, 81, 82, + 83. I would also avoid the VHF digital channels for the Coast Guard and I'm sure you have an active one in your area.