BCG:
Even in camping season, I don't know of any campground that is less than 30 miles from Pittsburgh.
The closest state parks, Keystone and Raccoon Creek, both close before the end of October.
However, take heart. The
Washington/Pittsburgh SW KOA in Washington, PA, near I-70 & I-79, is open until December 1st and
Rose Point Park near New Castle, PA, just off US-422, is open all year.
I've been to Rose Point Park twice but it's been about five years since my last visit and my information would be a bit "stale".
I've never camped at the Washington/Pittsburgh KOA.
Maybe another member can provide some information on these campgrounds.