It appears that the PO of my truck bent the actual frame of the truck using hte tow hook. The hook is actually slanted up in the front, and the back is pulled down, with a big bulge.

I ordered an ARB bumper, and will be installing it tomorrow, and im pretty sure you need that area to be flat to mount to, How should I fix this? cut out and weld in a flat piece? I have no idea

 

I have the same damaged section on my truck, it does't take much to make that part of the frame bend. Unfortuantely, I don't have an answer for you on how to fix it, but bending it back should suffice. I just dont know how to bend it back.

 

It appears in your avatar that you have a 99+ bumper which will require cutting the end of the frame off for mounting the arb. Perhaps you can get a heavy duty crow bar in there to bend it back. Of course rebuilding that part of the frame would be much better.