Toob,
That is a magnificent shot!
I've worked with all kind so extremes. With VFX, it was always something new. I'm one of the few people alive that has done live in-camera matte shots. The practice was common in the early 20th century because image quality really took a major hit when it was duped, so everything possible was done in camera on the original negative.
By the mid 1950's shots were largely done in post, rather than live and the old glass shot pretty much died out. It was an unforgiving technique. It either worked the first time, or not at all, and there were no second chances.
On Lonesome Dove I went to Angel Fire NM to create the master shot for the Montana Ranch. The idea was to show the change of seasons through a cross dissolve between a winter version and a summer one.
So one fine July day I found myself on a rise above a large meadow on a cattle ranch in the mountains above Taos, siting the shot while a log cabin and corral were being constructed below. Having sited the shot, I staked the tripod in place where it would stay until the shot was completed and an "easel" was constructed to hold the glass where I would paint the winter version. I would be carrying focus from about 5 feet to infinity.
A shelter was constructed to protect the camera and glass from the elements, and so that I could have some measure of control over lighting the painting, allowing it blend into the background beyond.
Part of the concern with this type of shot is that the landscape elements of the real location have to be matched in the painting or things will seem to jump around during the dissolve. Tree lines, rock formations, all kinds of elements need to join up. The clear areas of the glass need to line up to those portions of the location where action needs to be staged "inside" the painting.
I won't go into all of the steps involved, but I will say that nature and an idiot of a director played merry hell with getting the job done. New Mexico has amazing weather, and a major collision of storms arrived at the same time that I did.
My getting a painting lined up to the location was complicated either by fog that obscured the meadow or by a flunky who showed up to grab my lens the moment the fog lifted. The director had never used that lens before I chose it, fell in love with it, decided he couldn't live without it, and kept taking it to use at critical junctures. The only way I could end this nonsense was to tell the production that I regretfully had to quit as I couldn't proceed as things were. Suddenly the lens was mine.
Then the storm from hell hit. I was working nights to make up the time lost, painting away in my little shelter, 2/3rds of a mile from the nearest road, the outside a howling maelstrom of lightning, rain, wind, and texas gumbo. My trusty gas generator was powering the 9 lights that I used as a painting light while I painting in all of the snow that would dust the trees, cover the ground and the roof of the cabin.
A sudden blast of air burst through the door flaps, hit me like a five foot fist, literally tossing me into the air and then slamming me to the ground. I saw the 9 lights falling toward the painting and I managed to deflect it. When it hit the ground the lights went out and it was pure chaos inside as my equipment went flying everywhere.
And just as quickly, everything went completely still.
I was lying there, catching my breath, the only sound coming from the generator which was still purring away. My forehead felt wet and my first thought was that I had gotten cut. What I tasted wasn't blood but water. That's when I looked up and saw the beautiful starry night sky where the roof had been. It was snowing.
I figured that was enough for one day. I gathered up the camera, draped the glass, and hiked out of there into the darkness. My flashlight, along with some of my gear, had been blown into the deep deep darkness.
Want a good workout? Carry 100 lbs of camera gear at an 8500 foot elevation through sucking mud that goes almost up to your knees. Fortunately I didn't become anything's dinner before making my way back to the car.
Two days later, after more twists and turns, I lit the painting, called action, and got the shot.