I was aware that epoxy and a real shoot thru hull transducer would work. But considering that Lowrance has a disclaimer that shooting thru the hull would weaken the FF signal and degrade arches, I opted to go whole hog.
Also, if I used a real polyethylene epoxy like poly-welder
http://www.tapplastics.com/shop/product.php?pid=435&
there is no removing the transducer. EVER
/bing