I have a ton of questions regarding transducers, specifically the humminbird iceducer. So i ice fish a lot and contrary to most people that use traditional vexilar's etc...i have used the humminbird 345 ci with great success for about 5 years now. The unit came with the 60 and 20 degree ice transducer.
One of the problems almost everyone has when fishing in a group of fisherman is interference. I have specifically struggled when fishing beside marcum lx-1 and older vexilar fl-8's. I either cant pick up the jig on my screen or get a lot of distortion and cant see fish or my jig. I almost exclusively fish with he 20 degree cone because the 60 degree picks up so much that the readout is unusable even when not around other fisherman.
Most of my fishing is done in 10-25 Fow. I have played with the filter settings with not much success.
I recently bought a hbird 899 unit and am thinking about building a box for it, incorporating an external battery, and using it as an ice unit as well. Would the processing part of the finder work any better or worse then my 345 unit given the same transducer is used? I am assuming i would put the 899 into jigging mode and it would function like my 345?
I saw hbird makes a 9 and 19 degree transducer as well. If i used the 9 degree setting would i then potentially experience less interference all the while knowing i am seeing less of the bottom under me?

Would there be any advantage to me rigging up my hdsi boat transducer on a stick and using it under the ice? Does side imaging work correctly with the ducer holding still? Im specifically thinking of being able to go out on erie on the ice and look 100' circle around me, see a walleye and go over and drill a hole on top of him and catch him with traditional jigging mode? Maybe a pipe dream but it doesnt hurt to think outside of the box. It would also be cool to be able to sidescan schools of pan fish under the ice. I have reached under the ice and " shined" my transducer around in a circle to see schools of fish maybe 15' away, but hat is about as far as it works, And it makes your hands cold.

Its a lot of questions i know, but i had to just lay it all out there.