I'd suggest a different ship! No, really, the weapon convergence on the Clipper for fixed weapons is terrible, and Gauss Cannons only come fixed. The Plasma repeaters have a Turreted version, but be warned, the turret mode only works with multicrew, so you need a mate onboard. You'd be in a similar position with AX weapons too - fixed and turreted (I think the turreted MC are multicrew too).
So... You could try 2 medium Gauss Canons, but the convergence won't be great. The large hardpoints are too far apart, so you could try firegroups on each side, but that means combining a Large and Medium on each side, and the Gauss Canon has a firing delay. Might be interesting to try a large Plasma repeater paired with a medium Gauss Canon on each side... pretty colours!
I don't use my Clipper for Xeno (yet). I prefer the harpdoint layout on the Krait - 2x medium Gauss, 2x large Turreted Plasma or AX MC, 1 remote flechette, 2x Trident SLFs.