Yep pretty much impossible to mount a Structure Scan transducer on the trolling motor for a Humminbird unit. Structure Scan is a Lowrance product.
You can use a Humminbird SIDE IMAGING
transducer on the trolling motor for a Humminbird unit. That is very common for those with Humminbird equipment.
Since a Humminbird SIDE IMAGING transducer has a 2D sonar crystal for 83/200 kHz there is no need to connect the US2 transducer--just a useless cable and connections.
I have been using Humminbird SIDE IMAGING at the bow with a trolling motor mounted SIDE IMAGING transducer since I first started using Humminbird SIDE IMAGING.
Depending on the model of SIDE IMAGING unit you get there are a couple of PROPER transducer setups for that application.
One is a trolling motor PUCK version of the Compact SI transducer that the smaller display models come with. I used one of those at first.
The other is the HDSI version with a trolling motor mount.
I used the HDSI transducer on my trolling motor with a Transducer Shield and Saver mount (best there is).
Starting this year, I use the ONIX SI transducer on my trolling motor with the Transducer Shield and Saver mount.
The large one in this picture is the Compact SI PUCK:
This is the HDSI transducer with Transducer Shield and Saver mount:
This is the HDSI transducer and Transducer Shield and Saver on a Minnkota with US2: