I understand your pain. With the narrow tailgate (the tailgate is several inches shorter than the front of the bed) and a bumped out part on the right side of the TC, we have to put the TC as far right as possible - and it is still about 1 1/2 left of center. But DW and I figured out how we can load it as a team.
She drives - she lines up the truck the best she can, then approaches the TC. Right before she backs under I confirm we are PERFECTLY square and the truck is in the correct position. Back up 3" - check the distance between bed rail and right side of TC. Repeat. Maybe wave my hand to tell DW to turn the steering wheel 1 degree. Back up 3" - check. Back up 3" check. Adjust steering by 1 degree....lather, rinse, repeat until done. Total time - (including putting on tie downs, super truss, umbilical, etc) 20 minutes.