I took the main hitch bolts out, and left the rear mounted to the bumper. I then loosened the rear two bolts on each side almost all the way that bolt the bed to the frame. I took the lower shackle bolt out as I pulled down on the hitch a bit fitting the bolt through the cutout in the hitch bracket. Next I jacked the rear end up using the leaf spring against the seam to lift the bed as well until I could tap the bolt out above the frame. It was tight, but it came out. Maybe I bent the seam slightly by doing this which gave me clearance, but it looks straight still and I didn't have to flatten it.
This is just how I did it and remember to chalk the front tires and use jack stands. Good Luck.