You should really reduce the area you play on to 6' by 4' for regular games (3-5k) and deploy on the long sides (unless its chosen to play corners). A huge table could be great for very large games (>5k) or multi-player per side battles, but it's not ideal for regular games.
Could you post up a typical army list you use? And roughly what your opponent takes as far as you can remember? I'd standardly take a couple of Falcon formations in my Eldar army and they're usefull, but very fragile and I'm dubious an army heavily based around Falcons would be that competitive. An Eldar player should be assaulting a lot against a Tau player, trying to win a shooting war is is a bad idea for the Eldar and should go badly for them. There's a lot of things in the Tau list that would be good vs Falcons e.g. garrisoned Broadsides on overwatch.
It's not their ideal target but your Fire Warriors have AP5+ Disrupt Pulse Carbines, which they can use to put a blast marker on a vehicle target even if they can't damage it. You'd ideally make sure the target was marker lit to get the +1 to hit. How do you transport your Fire Warriors? Devilfish? Orca? Seeker Missiles from your tanks should hurt Falcons, if you get them markerlit (marker lights are really important to play well with the Tau).
Are you using version 6.5, the
current Tau list?
Sadly the Forge World Tau models are now OOP and ludicrously expensive secondhand, but you might like to take a look at some of the new and upcoming
Onslaught Minatures models, some of which could make great proxies.
Tau SUCK at engagements (apart from Kroot) by design, but Falcons do too. A formation of Fire Warriors in Devilfish would on average slightly win against a Falcon formation - getting 1.6 kills on average and scoring 2.6 due to outnumbering compared to 1.6 kills and score by the Falcons. You'd want to do the usual assault tactics of trying to make sure the target formation has more blast markers than your assaulting formation, ideally that your formation have none, getting another unit in position for supporting fire to help too, ect to increase the odds in your favour. It's not always going to be a good idea, but you should consider assault possibilities against formations that are bad at it.
Quote:
a 3k game is normally played on a 6x4' table either width-wise or corner to corner (depends on who won the roll-off)
Correction: if one player places the terrain then the other gets to decide to play across the width or corner to corner. If both mutually place the terrain or a third party does then it's the choice of the player with the higher strategy rating (one of the advantages it gives) to choose, only rolled off if the strategy ratings are equal.