One of the things Ive observed watchin trailer (5er or TT, doesn't matter which) folks backing into a site is they don't use all their limited steering angle available. Meaning they don't turn the steering wheel to lock when maneuvering.
They back in and pull out several times and their tires are always in the same track on the ground.
Use all you got is my motto
When I back "I cheat" Meaning if possible, I always want the drivers position to be on the inside of backing turn so I can watch the trailer tires as I know where I want them. My DW takes care of where the rest of trailer is. Im just steerin the tires. She finds what I could hit first and watches that area. Doesn't run around like a chicken with head cut off weaving her arms. Works for me.