The FCV295 is an outstanding sounder and deserves a high performance transducer that can utilize its full capabilities. That will come with a very substantial price tag, however.
I think your best bet to attain maximum performance would be to find a location just forward of the transom in one of the hulls where you can fabricate a pocket in which to mount a transducer. While not a contemporary spread specturm "CHIRP" sounder, the FCV295 has the capability of tuning the output frequencies. A CHIRP capable transducer will give better results if you use frequencies away from the traditional center frequencies of 50/200Hz for which "conventional" transducers are optimized.
The CM599LH (pocket mount version of the R599LH) would be a fantastic choice especially if you need to see bottom detail in more than 500 meters depth. However, if your fishing does not require very high performance in deep water, a much easier installation option would be to use a pair of tilted element transducers such as the B175H, B175L, and B175HW. These will be limited to 1kW but the B175L can easily read bottom to 500-600 meters or more. Even the high frequency B175H can read bottom clearly in 300 meters in my experience (I have one on my boat driven by the internal sounder in a TZT 3). The B175HW is a wide beam transducer that is especially good for seeing pelagic fish in the middle sections of the water column from 20 meters to 150 meters, which may also make some sense for you.
A much lower cost option would a single B164 tilted element. This is intended as a fixed frequency 200/50Hz 1kW transducer. It won't give you the full benefit of the FCV295s performance but does a decent job. By way of comparison, in the US a B164 costs about USD$1300 while a CM599LH costs about USD$4500.
Both a pocket mount CM599LH and any of the tilted element transducers mentioned above have the advantage of being nearly flush to the bottom and creating little drag, which is not unimportant on a smaller boat. They also would not interfere at all with putting the boat on a trailer if you need to do that.