There is no Twin Pines, there was a Twin Islands.
On the lower Beaverkill there Roscoe Campground, Butternut Grove, and Russel Brook Campground (just off the Beaverkill on a VERY nice trib). www.roscoeny.com has some contact info.

On the upper Willow there are a few campgrounds with most noted is Willowemoc Campground and Coverbridge Campground more info here http://www.livingstonmanor.org/camping.html

I know people has stay at all the campground and all have their pros and cons.

Joe Fox