Sailing Down the Lewis River
One of the limitations to the Bill Rollins theory is that he has never been to the Lewis River by the Merwin Dam, as far as I know. He was at the Ariel Tavern at the end of the CooperCon 2019 - his first visit to Cooper Country - but getting down to the river at the Dam requires entering restricted areas. I know I have never seen the Lewis River at that spot.
Bill says there is a boat launch area, but I can't confirm that. I do know the Lewis a little further downstream. It's not a big river. In fact, I don't know that any kind of motor boat can navigate the upper Lewis. Downstream, by Woodland, is certainly navigable, but is has plenty of logs, bends, sand bars, etc. As a result, no one can run it safely at night at speed.