I'm taking my SR Q17 this weekend and the in-hull option might work. I've always had better luck re: functionality with having the transducer actually in the water. My solo Northwinds has factory guide skid plates as well as the foam core which makes it hard to locate a flat spot on the boat's inner hull to place the skimmer transducer.

I like the rail site's option. I'll have to look at that as well. Still pondering options......