Check out Pa state parks here.
https://www.dcnr.pa.gov/StateParks/FindAParkByRegion/Pages/default.aspx Also while not quite in the southwest,Raystown Lake is a great campground.In West Virginia, there are several Corps campgrounds along I-79. Stonewall Jackson, Burnsville and Sutton. We have stayed at the last 2.Very nice along lakes with electric hookups.Also Trout Pond in West Virginia is a nice Forest Service campground with electric and a beach for swimming.In Virginia we liked Goose Point Campground on Philpott Lake.Some sites right on the lake with electric hookups.