Laker29 ... I just installed a Garmin Striker 4 CV on my 2018 Compass. The trick is to modify the plastic transducer plate on the transducer by cutting the extra plastic that extends beyond the body of the transducer. Then you need to cut a little bit of the posts on the transducer cover (kayak) to fit the transducer in. Finally you need to connect the transducer assembly to the cover posts ... use a pair of 2 Hole Straps used to hold 1/2 pipe ... it's in this video ...
https://www.youtube.com/watch?v=QKIU2lFFBjgThere will be a little bit of the transducer extending beyond the end of the transducer (1/2 inch ?) and you need to "force" the screws in that hold the cover to the hull, but not a lot.
Everything else is by the book to wire up you FF.
Any specific questions get back to me