You guys are way over thinking this.
Sith currently dominate this faction, thats how it is. ICly they hold the reigns and complete control because...well they were the ones doing all the conquering and leg work from the beginning. The NFU structure just came about as a way to support them.
The idea of Moffs as governors of planets makes sense, but to have them be on par with the Sith right now? No, that doesn't really make sense. Creating a Grand Moff position out of the blue just for OOC purposes seems kind of lame. The one NFU with real power above Sith(And even then its a First Among Equals power, so more of authority than anything else) right now is Avadreia who was appointed as a voice by the Dark Lord himself because of her capabilities, an IC gain.
Push it IC. Have more NFU do more stuff and gain power then push the agenda in a faction thread. I guarantee you that [member="Darth Isolda"] and the other two admins will gladly go along with NFU gaining power in a natural way that makes sense. If you're a general, simply RP gaining the loyalty of more troops, pushing yourself into prominence and forcing your way into power.
Thats the way to establish ranks.