Bed/body alignment issues

[87Skier]

I am fixing a few things on my Jimmy and found that the right hand side bed rail isn't square at the door. Measuring between the bed rails it is 1/4" wider at the front than the back, and the passenger door sticks out at the bottom, indicating this is the problem area.

I double checked by measuring crosswise between the opposite side and the measurements are 3/8" to 1/2" different.

Has anyone had to correct this on their blazer or jimmy?

I am considering using the door striker bolts on the driver and passenger doors and building a tube frame to pull and brace against. Would this be strong enough or will I need to add some additional bracing to the uprights?