A shooter from a very small farming town in Northwest Iowa built his own enclosed range decades ago using sections of the old clay composite drainage pipe.
His generation passed on, his property was sold, and new owners (along with the rest of the town) eventually re-discovered it when sections of the old pipe and the soil above began collapsing.
His enclosed range lasted longer than he did.

Ventilation has to be very aggressive to kill the mirage.   

Not in a shooting range, but I've fought that problem using laser interferometers to line up machine tools.  Indoors.

I think Stevens52 had the best idea. Digging a shooting range using a backhoe about 3 feet deep would leave a foot or so of removed dirt on the upwind side and would protect from wind somewhat. I do own an elderly leaking backhoe with a bucket about 2 feet wide.
Cost would be a lot less! Would have to dig a hole for my shooting bench about 6 feet deep and install a sump pump.
When it fills with snow, shooting would be problematic but I don't want to freeze my butt off anyway!
Don't know how wind blowing across the top would affect things. This range is in the middle of big bluestem which is about 5 to 6 feet tall.
I would have plenty of ventilation and lots of light with a built in dirt backstop at the far end. Could even extend it to 200 yards if I had the ambition.
As far as chickens are concerned, I prefer pheasants. They run back and forth in the range area and are constantly crowing and cackling. They are a lot prettier than chickens and I get along a lot better with my neighboring cattle and hog farmers who think,as do I, that chickens make good road kill!

Sometimes when we have a heavy snow year the trail to the backstop becomes a 3' deep trench (or deeper!).  The wind blowing over the top of the trench swirls down into it and drives 22 rf bullets nuts.  It effects heavier bullets but not as much.  I've read somewhere in the distant past of stacking up old tires to shoot through.  Seems I remember something about a few years worth of unburned powder left in the tires igniting after a shot and singeing some whiskers.

JS

I was at a test range in europe and they employed black poly corrugated drain pipe braced up on X bracing. The corrugated poly was perhaps 14" in diameter. There was a seperation between the shooting station and the pipe entrance of perhaps 1 meter and the target was also 1 meter away from the end
I thought that was kind of cool idea. Inexpensive and infinitely rebuildable.

Over 100yds even a 45-70 only has about a 4" height of arc.