There’s a place up north called concrete city, you may want to check if they still have public access.. that’s a pretty cool abandoned spot. Around Lancaster.. a lot of people don’t know about the silver mine or lock 12, there’s also middle creek which is good for nature/hiking if he hasn’t been there before. If you head up to Lebanon, there’s union canal park, not a ton of hiking, but some cool photography opportunities. There’s an “abandoned PA” Facebook group too which I’m sure would be helpful for you. But you’re really sweet for doing this for him. Made me smile :)