What u could do is take ur pickup and a small trl behind.Find a place u can practice backing,using only side mirrors.Crazy u say,haha maybe.But it will help u rely on ur mirrors to learn which way to turn the steering wheel to position trl.Alot of us have been doing this so long that we dont think about it,we just do it.But it does'nt happen overnite it takes time.Most of us would have a hard time backing around little cones and imaginary objects.But put us a corvette, a trk,and a chain link fence in the way.And we can blindside off a 4lane street into the dock no problem.
Once you get the hang of it, you'll even have fun going to jacked up places. When not pulling tankers, I volunteer to go some of out accounts nobody is willing to go too. Look at the bright side, you could be doing your backing test here.
I do the rodeo every year. I love going to shippers that have wide open docks and seeing how fast I can back in. I only do it while empty and while there is no people or equipment around.
Try stopping every few feet while backing to not only see where the trailer is but what you feel you need to adjust to get it in. During the test you only get so many pullups but you can take all day while going back. Don't rush it.