If I am mounting my 1199HD's (both SI/DI models) at the dash, what splitter cables I will need if I want to select a certain unit for side imaging or down imaging, etc? Or if I want left side imaging on the left screen and right side imaging on the right screen? I have a HDSI ducer on the back of the boat and shoot through puck in the bilge, with a splitter cable going to the current single unit at the dash.