Connecting fishfinder to trolling motor wiring

I attached my transducer (Fishmark 480) next to the prop and to keep
things compact, want to attach the screen right on top of the trolling
motor (using high quality electrical tape :-)).
To keep wiring neat, I was thinking of splicing the power cable
attached to the motor (under the handle) and routing the fishfinder
power directly to it. Anything wrong with this setup? I'm concerned
about potential interference.
I currently attach the finder directly to the motor battery and all
works fine except the fact that the boat looks like Edison's lab.
(Does anyone make a wireless transducer??)
BTW the Fishmark is AWESOME, I just look at the fishies on the screen
scroll by and sometimes don't even have time to fish.