you should be able to handle that..............
silicone where you mount the transducer, if you put it on the hull, if on the trolling motor, don't worry about it.
you might want a different battery supply for the finder though,since the magnetic interference with the TM and the finder on a single battery might cause you grief.
Be sure to run some conduit for the power to the battery, just to make it clean.......
Have FUN.