I would leave the upper deck between the 20-yard lines available if you do that. Those are good seats. If you tarp from the 20s to the ends only, you get something that looks like this:
Now you've just set the capacity to around 48,000-50,000. Which is "right-sized". Put more Pitt logos or designs on those four tarps and you've got something.
I like that approach. I would definitely be in favor of employing it at Heinz Field.