Thanks for the responses. I decided to go with the two transducers. I spent $2600. on the unit. I don't want to live with screwy images because the outdrive is in the way. For $240. I bought another transducer, an extension cable, a y cable and the bracket.
I am partial to thru-hull transducers because (I think) they seem more professional.
I looked under my boat, pondered where I would install them, thought about all the work that would be required, realized that if I got it wrong I would be stuck with a cluttered return forever. Needing to find a saw that will cut the fairing block just perfect, etc.
Then I thought about how easy it would be to simply make four holes in the transom and mount the transducer and I would be done. Worst case? I fill four small holes.
So, let's see how it goes.