Dear Larry,
I regularly make breads, including Reinhart's pan de campagne, at 7,000 ft.
At this altitude, the air usually holds less water than at sea level, so
you will have to watch the dough closely as it rises to be sure it doesn't
form a dry crust on top. I sometimes leave a very wet paper towel on the
surface of rising dough if it is in a large bowl and there is a lot of air
space between the dough and the covering. I always use plastic to cover,
never cloth, to avoid drying out the dough. If you are doing the rise in
bread pans, oiled plastic wrap will work well.
Your dough will also rise faster due to lower atmospheric pressure at
higher altitude. You might have more control over the faster rising if you
don't form the loaves until Saturday morning when you are at the higher
altitude. Once the dough is in the pans it is pretty hard to punch them
down and start over, if you see what I mean.
Mike Avery bakes at even higher altitude and is an extremely experienced
baker so I am sure his comments will be particularly helpful to you and he
will correct any erroneous information I may have given you.