My frame was tweaked a little, droping one side about 1/2" lower than the other in the rear. I used a flat piece of 1/4" steel to brace it back up and then slid the tank to the steel.
I will have to modify the steel piece in order for the inside back bumper bracket to work. I will also fab some hinges for the tank straps and mount them to the steel piece.
As you can tell I gained quite a bit more space by moving the tank back.
Before
After
