4/5, EBJ are squishy-ish so may want to stay at range. I prefer to fight closer, but the EBJ has the speed and cooling to pull this off. Good for invasion.
Since you can only fire 2 at once without ghost heat, what is the benefit of having 5? I would just do 4. Left side/right side fire groups, should be able to shoot more often and get better DPS: Here's a version that gives you bunny ears, but higher hardpoints do help quite a bit for hill humping and shooting over edges: