I think there are some members here on SBO that have their boats at Stoney Point but I don't recall who they are. Looking at where you are, have you tried Lake Wallenpaupack? (Am I spelling that right?). I used to take my trailerable there so sail sometimes. It has a free public ramp you can launch from. It's not s bad lake to sail on.
While I'm close to Stoney Point I don't know much about the marina there. It is located in a fairly wide section of the Hudson. You may want to be mindful of the tides but it should be a decent area to sail. I have no idea what kind of launch facilities they have there.
Down lower on the river, there is a public launch under the George Washington bridge, at least there used to be. I haven't looked in quite a few years.
dj
