Well, I've tried a number of experiments, ranging from
shading the light source (with a piece of plastic shopping
bag material!) to almost nothing but bounce lighting (off
a wall to the left side of the subject). I can get rid of
the over-exposed areas, but then I loose the "long shadow"
effect that I was originally trying for. Any form of diffused
lighting that I've come up with softens the shadows to the
point of making them so indistinct that the effect is lost.

Gotta get some more lighting gear too. Clip on lamps with
100watt bulbs and sleeping bags draped over chairs just
don't cut the mustard! :-)

Thanks again for all your input; I've learned something about
lighting as a result.