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He might spend a lot of time on the road, but being from PA as his sig states, I can guarantee you he has never had full hook-up here. Electric only, water spigots, and dump stations. No PA State Parks have full hook-ups that I've ever heard of. That's all we stay at when we camp.
And yes, to the OP, by all means please use a hose. Man! Some people are inconsiderate. Who wants to be next in line after that????
Actually, I've camped at Little Buffalo State Park in PA, which does have at least some sites with water hookups. I believe this was a former commercial campground that the state bought. Also, in regard to MD, the North East loop at Elk Neck is full hookup -- only one I know of in the MD state parks.