Well... I honestly meant to post a thread about my solution for blocking out the neighborhood streetlights and porch lights right after I'd finished making it. But hey... I'm only a little over three-and-a-half years late.
In my circumstance, I own my home... but since I'm in a mobile-home park, I'm not allowed to erect a permanent structure in my (gravel) front yard (and don't have a back yard), so my "driveway observatory" has to be put up and then taken down each time I use it. Each of the four separate 7'x10' panels is made from PVC tubing that's solidly glued together, and each panel has a nylon "privacy screen" that's permanently attached to the PVC frame via grommets and zip-ties:
The seven-foot height is exactly enough to block all of the local lighting fixtures, and the screening is opaque enough to keep the neighborhood streetlights and porch lights and drive-by car headlights completely at bay. Once I'm in it and observing / photographing, my dark-adaptation is completely preserved... so as you can well imagine, as soon as I'm settled in and under way, I can't get the grin off my face.
Over the years, I've been lucky enough to have some seriously dark sites within an hour or two of where I was living... but this is only the third place I've ever lived, where I could realistically observe from home. I've been here for twelve years, and while the skies here aren't as dark as I'd like them to be (whose are?), they're not *too* bad. To my west, there's an unpleasant amount of sky-glow from a nearby city (~seven miles distant)... but the sky's entire east-facing hemisphere is pretty much mag 5.3... so as an example, M31 in Andromeda is just above the edge of naked-eye visibility.
Of course, starting with the first night I spent here, I immediately began thinking about ways to block the neighborhood lights... but it wasn't until about four years ago that I finally started homing in on a workable solution.
The obstacles were significant; the most serious one being that I live alone, so whatever I devised, it had to be something that would be large enough to encompass all of the necessary equipment, and high enough to block all of the surrounding lights... but also something that I could easily put up by myself, and do so in no more than about fifteen minutes. Otherwise, I'd never want to bother with it.
So metal pipes were out... but the 1-1/2" PVC tubing from Home Depot seemed strong and light-weight enough... and it was conveniently available in ten-foot lengths. I did have to have the privacy-screening panels custom-sized, in order to have them fit inside the finished 7-foot-high PVC rectangles (the "stock" height for the screening is eight feet). And the seven-foot height was necessary, because if they were any taller, I couldn't lift them high enough to clear the ground and carry them by myself. The total cost for the whole setup was about $400... which isn't too bad, for a private "observatory".
I keep the four panels outside, leaning against the side of my house... and to assemble it in the driveway, I just fasten them together at all eight corners with 24"-long, 1/4"-diameter, rubber-coated "twist-ties", which I also found at Home Depot.
Obviously, this is not a structure that will remain standing in more than about a ten-mph wind... but fortunately, it's not very windy here, and what wind there is completely dies down -- except for maybe ten nights a year -- about an hour before sunset. For added stability, I place a 5-lb sandbag at each corner: