I wouldn't recommend using a jump pack but instead a dedicated battery inside a battery box. Then you could mount your sonar unit to the battery box. Set up a charger at home for charging. I use a CTek and have been very happy with it, as are the other reviewers.
See last post in this thread with link.
Nice looking Zodiac SIB
Somewhere in the past I have seen where others have mounted their sonar sending units to a pole and used a clamp over the transom. I have mine permanently mounted, and just undo the connector when I want to remove my electronics tower.
Transducer goes on the starboard side due to prop rotation.