While it might appear that there is minimal damage to your GT, Fieros are notorious for hiding severe damage under the panels, as the panels can pop back out.
Before you start making any plans to restore the car, get it home and pull the whole rear apart. Look for more severe damage to the frame. Being as you live in Tx, hopefully you're lucky and your car is rust free. That might have helped the rear structure.
But if a truck plowed into you doing 40mph, I hate to be pessimistic, but I have very serious doubt that your Fiero survived that.
I do really hope I'm wrong though. Please keep us updated as you progress here.