Puma STS 15 or 16″ bow graph

Anyone running a 16" bow unit on their STS? Does it fit and if so on what mount? I'd prefer the low profile of the gimbles on the fiberglass but assume I would need an aftermarket mount to accommodate. I ordered my boat without graphs with intentions of building it myself over the winter and am planning now. I have 2 Lowrance HDS 12's at the console and, if possible/practical, am thinking either dual HDS 16's, HDS 16 lower and HDS 12 upper, HDS 12 lower and Garmin 12" upper. Any feedback would be huge. Thanks