with the FCV1150 i would pick a transducer suitable of doing bottom hardness.
for the DFF3D you want which ever transducer will fit. pocket mounted makes me think you want the 165t-CM54
maybe a good option would be the 165T-PM542LHW, you can transmit 2kw on the low and high wide channels on the 1150, and run DFF3D, all from one transducer
make sure you add an SCX20 for heaving compensation , both the 1150 and dff3d can use it