There's a weird little spot out on the Western Coventry/Sterling line, I think it's part of the North South Trail, but you can get to it on Greenhouse rd. It's an area that's been recently clear cut to help rabbits or something (there's a sign there that explains it) but it's public land and its dark as hell out there at night with a nice hill to climb and unobstructed sky. If you're coming from the RI side it'll be a small parking area on your right and you'll see the opened up area from the road. It's a dirt road for a section so be ready, but it's fairly well maintained.