Kevs57:
Your bed has been modified so only you looking at the bed can decide if it is still secure and safe. Why not install angle strip bolts to connect bedsides to cross sills and verify the 8 bed-to-frame bolts still attach the sills to the frame. Then you know it will be right. The plywood is not quite as wide as the bed, but you can place a 7/8 wide wood spacer under each angle strip to center the plywood under the angle strip edges. Bolt the plywood down to the cross sills and front panel using the holes that originally attached the bed strips and you should be safe.
Mar-Ktech
