To report back on this, FYI I was not able to get this to work. Once I finally thought I had, I pushed it to our dev branch and found that it still appears broken on different hardware. (i.e., what appears to be resolved locally on my machine is not working on others’).
Suffice to say, the water plugin is borked and does not work. It has not been updated since releasing as experimental 0.1 as far as I can tell and appears to be dead in the water (pun intended!). So my advice to anyone considering this would be to avoids UE’s water plugin entirely and either build your own water shading tool using splines or obtain one via the marketplace.
Working with tools that remain experimental in perpetuity is not worth the headaches and the lost development time, it would have been honestly been less harmful for them to not release this at all than to release a broken version that can cause wreak havoc on your landscape and never finish it.