Check out sternmate.com
There are pics of a Ranger step install there.
Measure your length to be sure it will fit and not get hit by the engine at any trim or steering angle.
I have seen others just screw it to the step (if the step is long enough). Measure twice, make that about 5-10 times, drill once, countersink holes, and seal it all with 3M 5200.
Since the LSS transducer has temperature, a shoot through hull epoxy mount in the bilge seems to be most common for the 2D transducer.
God does not charge time spent fishing against a man's allotted life span. - Indian Proverb