WOW...if the frame is bent down 6" then you will have trailer structure damage like in the sidewalls and back wall pulled loose from the floor or floor pulled loose from the frame. If it didn't then look close at the roof and top of the sidewalls above the bent area.
I would have someone with this type of experience check it all out for you.
A experienced big rig trailer repair shop can repair the main frame rails/cross members....stronger than OEM.
What does your insurance company saying ??