gmack I read your post and watched your video. Liked. So I ordered the Hengs Vortex II vent fan from Amazon. I managed to install it myself after a bit of trial and error. Once I figured it all out, then everything went together much easier. Kinda hard working with your arms over your head, especially in the tiny bathroom of the Sunseeker 2300.
But, once she was completed, the thing worked beautifully. I have already used it as a type of 'attic' fan. I set it on medium speed and open the other vents and the kitchen window. It draws a nice cool breeze that you can feel even while sitting in the dinette booth (of course, the bathroom door needs to be open).
Thanks for the original info and video.