I could probably epoxy it under the rear seating area so it didn't get kicked around, i just didn't know if I'd want to do that and lose out on the water temp feature... but the hull's a very thin plastic type, so it would probably still be fairly accurate after a bit of time in the water.

@Blue Duck: Did your portable come with that rod, or did you buy or craft it? I have seen some side mount transducer brackets and I guess that is a possibility too.

WOuld somethign like that be better than the Trolling Motor Mount though? I guess with either of the other two methods if I decided to fish a lake with a no-motor policy I could still use my Fish Finder.