It's nothing hard to achieve.. To pick bottom signal in 100-200 kHz signal in 200m of water is easy.
The DownImaging part is just a differently shaped transducer..
But the spatial resolution of your sonar beam in 100kHz signal will be poor.. You won't obtain "HB" quality images with this setup, and at 200m depth, the angle of the beam will lead almost useless pictures.
To have a descent angle of sonar beam at 100-200 kHz, you would need a very long transducer, like a meter long.
Just check the LSS2 tranducer which is already a beast at 455 kHz.. quadruple that size for 107 kHz