Yeah, if you're planning to use Boba Merc and Deliah, then a Muun Tactics Broker is DEFINITELY a good idea. Forget the Gonk Droid though. I would use either Kel Dor BH's or an Ugnaught Boss. The Gonk won't really help you at all. Lobot is always a good choice, as it will give you Override and the customization options.
With Fringe only pieces, there are plenty of great options. As SynGates pointed out, a couple of Bounty Hunters will be a must, as you can bet people will utilize those. E522 Assassin Droids might also be good. The Felucian Rancor might be a solid piece too, but it's hard to say for sure, since a large majority of Fringe pieces are shooters, so Parry won't help as much. However, a 20 Defense and being non-Unique, plus all the HP and Regeneration will make it tough to take down.
Oh, Wicket will be another piece that would probably be good to include, just watch out for opponent's Accurate Shot pieces.