with a pair of LPL as "primary weapons" I would tend to go with the lb 20x and something like 2:1 lbx rounds vs standards. so with 3 tons of ammo I would take 2 tons of cluster 1 ton of standard ammo.
my thought is you fire the large pulse lasers as you close, which thins down and or punches holes in the armor, if the armor isn't sufficiently breached, you fire 1-2 standard rounds until you get to medium or shorter range with the 20, and then switch to cluster and finish him off with paper cuts. as you are going to typically hit with ~12 sub munitions per shot that connects.