Competing with an IP

Competing with an established IP is difficult.  Even with players generally unfamiliar with source material, a quick search on Google can net a wealth of information, effectively spoiling plot.  This leaves gamemasters with a wealth of background knowledge that could be exposed at a moment's notice, or leaves the gamemaster heading into uncharted territory in a manner that leaves the players feeling like the GM has moved too far away from the established IP.

This has become a debate I've been weighing as I've moved from my November project, a NaNoWriMo novel about the American Civil War to a Traveller campaign as requested by one of my players.  More specifically, I'd been playing a hint of Traveller and decided I particularly liked the setting enough to try my hand at running a game in the universe, and the player's request for a Mech Combat-based RPG was perfectly timed with my own whim.
My first option was running the game within a slightly altered default Mongoose Traveller (MGT) setting: the year 1115.  The problem with this is twofold: per established canon, mechs did not exist in any military capacity during this period.  They primarily existed in two eras within lore: the New Era, where they served primarily as infantry support platforms, and in the ancient era, where there's not particularly much support.  Though both were interesting, neither setting particularly enthused me.  This led me to the second option: developing my own spin.
Two official Traveller campaign settings have explored this option: AD 2300, where a hard sci-fi setting was applied to the early colonization of space; and GURPS Traveller, taking place in a hybrid between the Classic Traveller setting and the New Era.  Both appear to have gathered a small number of fans, and appeared to create a hybrid setting for their particular niche.  Given my usual players' inexperience with the MGT setting, though, I also wanted to leave the door open for any of them to take up the mantle and explore the setting more deeply through their own lens.  I have a group that has traditionally not been comfortable running games aside from the player I previously mentioned, but have occasionally exhibited the divine spark of creativity necessary to fully realize a game world.  If any of them begin fostering this spark, I didn't want them to have to un-learn anything I present in order to bring the world to life themselves.
A second option reared its head: finding an era of Traveller that had not particularly fleshed out, and build into it.  The 1115 setting was ideal for this.  The galaxy is on the cusp of at least six different major wars, and has a rather cataclysmic event that forms the bridge for the New Era games of MegaTraveller.  MegaTraveller canon leaves a rather large gap between the years 1140 and 1220.  During these years, a large number of events could happen that do not contradict established canon, but that aren't available on a wiki floating around on the internets.  By setting a campaign in this time period, I establish a continuity in a gap that hasn't been fleshed out, but that also builds familiarity with the universe outside of it.  I liken this to Bioware exploring the Old Republic rather than setting their games firmly within established canon -- the basic concept of the universe is already fleshed out, but is largely irrelevant to plot.