One spot not yet mentioned is the cowl. It likes to rust on either side at the bottom and can rust just above the brake booster area, kinda behind the hood hinge.
The cowl extends down both sides behind the rear of the fenders, it ends about 1/2 to 3/4's of the way down.
Even a blazer being sold as "rust free" needs to be checked close.
Good luck in your search and have fun
