ahskip1,
Welcome to the forum.
You should be able to mount the transducer off the transom but you will lose 2d and SI at high speed. The other alternative is to mount it down by the drain plug and water intake. This will give you good results but will make the transducer more succeptable to hitting structure, stumps, limbs, etc. If you fish areas with lots of stumps, this may be a risk, and the transducers are not cheap.
You need to go out on the water before you install and check the turbulence around the transom when you are running at trolling speed and running fast.
Most guys have mounted them on the transom or jack plate, but tend to lose 2d at speed. So they install an in-hull (shoot-thru) transdcuer with Y cable in the bilge to get good 2d readings.
Just some thoughts. Do check out Dougs site though. He has more experience with Bass Boats!
Good Luck and let us know what you decide. Picts are always good!
Robert