Sidescan fishfinder compatibility for a 2017 Hobie Outback

I fish a lot on Rivers and would love a new sidescanning fishfinder, but I am can't seem to find anything online about whether it would work through the transducer mount. It is also not as big as the newer Hobie Gaurdian transducer mount. I know the BerleyPro external mounts exist but most of what I have read about them are negative experiences.

Hoping someone out there has experience and could point me in the right direction.

what does your transducer plate look like? 

it doesn't flex up and down right?  it is like the one on a Hobie Compass I think?

I have a side scan transducer with my Hummingbird fish finder. It also has a downscan and standard sonar. I’m also one of those unhappy BerleyPro customers.
I don’t know what your setup or kayak is like, but I suggest that you have the transducer under the kayak without any obstructions. Even sand collecting around the transducer can impact accuracy.
I have a Revo 16 and I ended up engineering a setup like that. It’s not simple to build, but it works great. I never had to remove it and it never moved. My main concern was damage to the exposed transducer, but it’s build like a tank. No issues at all.
In a nutshell, I cut out an opening exactly the outline of the transducer, and then used some hardware to connect it to the Hobie transducer plate. The final and most critical part was to fabricate a custom piece of closed cell foam that filled in the remaining kayak’s transducer cavity. The foam prevents the transducer from getting pushed in.

I hope this helps. Let me know if you need more details 

Side scan on a kayak is kinda useless.  We generally don't go fast enough for it to be effective I've  found anyway.