Rhino, the transom mount Compact SI transducer for the 798 is all plastic. Yes it is fragile as compared to the HDSI transducer mount.
Jenga, the best application for that mount and any other SI tranducer for console use on thin hull fiberglass bass boats capable of 40 mph+ is to mount the SI transducer above the hull bottom for off-plane use and add a shoot-thru 83/200 kHz transducer (XP 9 20) inside the hull for on-plane depth reading. Connect the two transducers to the display with a AS SIDB Y cable.
What that does is disconnect the 82/200 kHz from the SI tranducer and connect the shoot-thru in its place.
Many bass boat owners that have jackplates mount the SI transducer to the jackplate.
For slower craft, a transom mount setup works fine for SI/DI/2D.
I'm not familiar with your particular hull design, but if it has sponsons like the newer ones, you have to mount it lower than just the standard mount allows.