Welcome to the Humminbird Side imaging Forums ifishmo2.
Port or starboard side really doesn’t make a difference on a boat with an outboard motor unless you run in reverse a lot. That is mainly for inboards with propellers forwards of the transom, so that they will not push aerated water across the transducer.
With the location of the trailer bunks, the DI transducer location may be your best bet. You won’t know if the livewell intakes will block any Si sonar until you get it all installed and test it. Set the SI Range menu to 20 feet and look for a constant line that runs parallel to the center zero line as that is how it may show up.