Hummingbird makes a 360 transducer for high end units.
I think all of the major manufactures make side finding units. Going to have to spend a little more and have room for another transducer. Have you tried a camera? If the water is clear enough it should work as well and not as expensive.
I may be a dumb ads, but what happens of you point the transducer "out" instead of down? The ping its still going out and coming back, just from the side. ..
looks like its going to be a hb helix 5 with the side imaging, atleast he will be able to set way points. i think he would prefer the old side finder that bottom line put out back around 2000, just a fish icon showing the fish 20 foot out left or right. they had it on the upgraded fishing buddy as well. i notice on my lowrance that the side imaging isnt that great if your just anchored, you need to be moving so not sure how the hb will work