On my Micro-plus, I mounted the transducer as shoot-thru-hull, i.e. fixed to the inside of the hull, and it worked fine. I used an empty plastic bottle to cut a collar that fitted around the transducer, placed the transducer in it and filled with araldite to cover the head. Move it around a bit to get rid of air bubbles and wait for it to dry. Obviously, being quite dense, this takes a little time.
You will, of course, still have to cut the floor to access the inner hull.
On my Warrior, I have used a transom mount transducer which is much easier to fit and this has proved equaly as effective.
Hope this advise from one still learning is helpful.