I have a Hummingbird Fishin' Buddy as well. It solves the transducer problem and getting in and out of the tube is a breeze.
I got the tube-strap-on holster from Cabelas and it workd like a charm.
Totally portable it can be used on a tube. toon .canoe or runnabout with ease.
Side view technology and bottom structure are the main features but it shows fish a well.
Best option for a tube or tune in my opinion.

DuFf