My group also arrives at PBH on September 18 for the week too, but we have just one night for HHN.
If you’re concerned with social distancing, the house queues will be far worse than the holding area. The holding areas typically have room for people to spread out, and will only pack up when the areas are released as people rush to the houses.
Also, I suspect that people will be packed at the park entrance before the event begins. So if you plan to start HHNs when it starts, your two options are the crowded front entrance or the less packed holding area.
Since you do have Rush Of Fear, and will be attending multiple nights, you could conceivably wait to enter HHN after it begins, and the large outside crowd has entered.
My advice is to be in the park prior to closing. You can inspect the holding area before entering them, and determine how crowded they are. If they aren’t too crowded, go ahead and enter it. If you consider it too crowded, leave the park and come back later.
One thing you can’t do is enter a holding area, and then leave it before release.