Howdy, I can only speak to the Revo 11 since that's what I have.
The Scotty Flush Deck Mounting Bracket (No. 244) will just barely fit on the gunwale just above the rudder up/down handles. That's about the only place where the gunwales are wide enough to fit it. It also happens to be a good place to put rod holders and a fish finder.
I also put a Scotty No. 444 Compact Threaded Deck Mount in the small cup holder. Perfect fit.
Many people will mount their fishfinder in the sail mast forward of the pedals. For that, one good solution is to use a Ram Wedge Mount (Part ID: RAP-354U ). It should fit right in there. I prefer my fishfinder at arm's length so I have mine on the gunwale.
The Hobie rod holder extensions are good for the built in rod holders behind the seat.
That's what I've done but everybody I know has a different setup, so I suggest you do a google image search for 'rigged hobie' or 'rigged revo' and you should find a lot of ideas, from simple to simply awesome.
A few pics to get you started:
