Flash photo of distant subject with close obstacles

Question

I am a very inexperienced amateur user of Photoshop CS, but  I have been experimenting with a way I have devised (though I am sure it is not original) of dealing with what I imagine is not an uncommon situation, and should be most interested in comments from the experts.
You attend an indoor event — a ceremony, a performance — and photograph the goings-on on stage, using just the flash from your camera, from a distant and poor vantage point behind other spectators. When you examine your picture, you see beautifully-lit chair-backs and rear views of people in the foreground; in the background, so dark as to be almost indiscernible, the event you wish to record for posterity.
What to do? You open the image in Photoshop, increase the exposure-setting drastically, fiddle with white balance, contrast, saturation. You now have a decent image of your desired subject, but with huge chaIr-backs and backs of spectators' heads in almost flat, brilliant white dominating the picture. So you try cropping, but discover that there is no way of cutting out the chairs and spectators without decapitating the actors or cutting their legs off.
Now you try darkening the chairs and spectators — with the burn tool or by selecting them with the lasso and using the Brightness/Contrast adjustment. But because the combination of close flash lighting with greatly increased exposure-setting has removed shadows and texture, you now have quite unnatural-looking flat grey obstacles in the foreground.
This is what I have started doing: I save two versions of the image in Photoshop, one with greatly increased exposure-adjustment (as above), the other with something like the unadjusted, or even slightly reduced, exposure. It is important not to do any cropping at this stage, because the two versions of the image must be spatially identical. In the dark image, I use the lasso tool (with feathering set to about 10 px, but experimenting may be necessary) to select the foreground obstacles and copy them. (It is likely that they will be out of focus, and again experimenting with whether to select around the inside or the outside of the blurred edges is desirable.) Then I go to the bright image, select the obstacles again and paste the previously-copied, modestly dark obstacles over the brightly-lit ones.
Now I do any cropping of the bright image that may be desirable; the dark one should be no longer required, but I keep it alive in case I have to modify my selection and try the whole thing again.
Unless I am quite lucky, some detailed retouching with the clone stamp tool or the eye-dropper and brush may be necessary around the edges of the pasted objects. And, of course, I use duplicate layers at various stages so that I can go back if necessary. But essentially I end up with a properly-lit main subject, with natural-looking but unobtrusively dim foreground obstacles.
Is this a common practice? Or are there better ways of dealing with such a situation?

Answer 1

Thanks for this, Printer_Rick. The trouble, though, is that there is no
way of adjusting exposure (as distinct from brightness, etc.) once the
image is in .psd (or JPEG or even Photoshop Raw) format. At least that
is the case in Photoshop CS, which is the version I have.
Because I only have CS, and because my Nikon camera is later than the
latest one whose Raw files Photoshop CS can handle, I have to work with
Raw files in a rather complicated way. I have to convert them to .dng
format by using the one version of Adobe DNG Converter that is both
early enough to work with Photoshop CS and late enough to handle my
camera files. Then I can open the .dng files in Photoshop and adjust
exposure.
I have tried to convert .psd or Photoshop Raw files back to .dng or some
other format that will let me adjust exposure, but have failed. In any
case the masking would not be preserved. So it would appear that until I
can afford to upgrade to Photoshop CS4 or thereabouts, I shall not be
able to avail myself of your simple and elegant procedure.