Campstugots: I bring my target with me when I go to Extreme Archery in Mammaroneck. Their backstop works with the bolts. I am also very considerate with the loading time etc., and don't even start to cock the xbow if the archers are near to completing their round. I'll check the places you indicate but I don't hold out any hope.
Elmo: I called Pro Line in Queens, NY - they don't allow Xbows at the moment but are in the process of modifying their walls to allow for xbows - they told me it would be at least a month or so before they are finished.
Bottom line: I'm still at the same place I started - In New York you cannot practice shooting your crossbow unless you have your own backyard or a friend's backyard. I would even go as far as not recommending any newbie hunters out there to buy a xbow. Moreover, from a safety standpoint, it means that you have guys going out into the field who have not learned to consistantly, safely and accurately fire their xbow. Awesome.