That's where I'd put it.
In order for SI to work properly, the transducer needs a clear
line of sight (left and right).
Depending on how your outboard is trimmed, you may have
to trim your motor up a little bit to prevent blocking the left SI.
I would install a transducer plate. That way, you only have
to drill two holes through the transom. You can then move
the transducer around, screwing it to the plate.
Some people glue the plate on, but me personally, I would prefer
strong, stainless steel screws/bolts.
Few transducer installs are perfect the first time.
You may have to adjust it (up and down), a few times
to get the optimum height for the clearest images.
Good Luck.