there are walk-in sites at Kentuck Campground, signs for trail to the left just after the second bridge from the "main" place (headed towards Pgh). Very convenient, though the rest of my party found the showers 'disgusting' I found the water to be very hot and scent free, thus lovely. The pet sites were $25/night I think, or $50/night. Hubby paid, or I'd know better, but it's easy to reserve online. Almost nobody was at the walkin sites when we were there last weekend (rest of the place was PACKED)
Some sites a little further in at the same campground (vehicle access, but spitting distance from the walkins and I'd consider just as convenient) are designated "pet friendly" sites, however one must transport one's pet via MOTOR VEHICLE to said area. Oh yes, they'll be hearing from me. That's the one down side I've found to their new pet "friendly" policy - they've decided that while pets are allowed on the GAP, and they're allowed in certain areas at the campground, they're not allowed on the inbetweens (deliniated by no markers or signs, either, so that's super easy to figure out). sorry for the out of place rant. just peeved that they assume all pets must be transported with motors.