Question: If the seat belt brackets are unbolted will the rear mounting screws be accessible?
Thanks for any help.[/QUOTE]

Unfortunately, removal of the 17mm bolt that fastens the belt to the side of the seat will not improve your access to the rear seat track bolts.

Brother, you appear to have a bit of a tough task ahead of you.

The only suggestion i can put forward is to work the bolts from the underside. I believe the seat track bolts go through the floor and are visible from the underside. Perhaps you can get them started with a pair of Vice grips. Not sure if it would work but at least it may be worth a try.

Please keep us posted.