How to Fix a Sagging Tub???

When I bought my jeep i drove it for a month before the slamming noise in the rear made me take time to look at the cause. The Cause? There was not bolt or body mount holding the driver left corner down to the frame. It was freely banging against the frame. Well this has caused the metal to stretch and now the corner sags. At first I shimmed it with an extra body mount to raise it and it worked until I put a two inch body lift on. After the last trip the Corner now sags a full 2 inches lower than the right side. The Whole support rail is now bending and bending bad. I am going to use an 1/2 inch thick piece of steel to support the rail. I know this is overkill for a support, but I am tired of the sagging. My real question is, is this going to help this problem or cause something else to happen? The piece of metal is about 8 inches long, by about 3 inches wide. Is there a different way to fix this?
Thanks for any help
Dan Stewart 1963 "Caloosa Jeepers" member