you will never truly be able to stay at range. Alas it's one of those annoying things in ACTA. Minbari need range, so are fast, narn need to close, so are slow, go figure!
As Nomad said, you have to make your enemy pay for trying to close range. The Tigara and Trolligan both have good close up weapons, mix them in with your fleet, all stop as long as you can to hang back, then as the enemy closes, try blasting right through their formation to the other side. you will loose a couple of turns of best shooting, but you should still be alive, chances are you will turn as fast if not faster than your opponent, you could even try an all stop and then all stop and pivot. Warning however, this will not work against ISA, Vree, Shadows!