Wetmount install condundrum, Loctite Putty?

[Durwood101]

I have a Airmar P79 transducer that I want to install in my Hobie Outback. I've done some research on this for adhesives and it seems the overall success has been attributed to using Marine Goop. The problem I have is the case the transducer sits in ( similar to Bob's 3-4 inch PVC Pipe transducer case for his wetmount design). Anyway, I've tried twice now, and the thing I cannot seem to do is get the bottom of the well to sit flush with the keel.....due naturally to the curve of the kayak. I know some of you have used a sander to shape the bottom of the pipe, but I'd like to avoid that if possible mainly due to not have a sander to craft the curvature. There is no way I can build up the marine goop enough to fill that 1/4 inch gap at the front and back of the cradle ( the goop just doesn't have enough "body" to do this) I was thinking about using this LOCTITE putty to fabricate or mold a thin roll into this crevice to fill the space. This will allow me to use the existing Airmar P79 cavity well to house the mineral water and transducer. Any suggestions or advice?