I have found these bright yellow, magnetically mounted, telescoping devices pretty handy when connecting to the trailer unassisted. I bought the first pair from Northern, but found that the plastic bases did not retain the magnets well. The second set (yes I thought that they were worth another $9) came from Harbor Freight and they were actually much better quality. The base is all metal and more durable. One of my trailer trailer ball receivers has a fully domed top so the magnet has to attach to the flat lip around the hitch, but that can be adjusted so that the approach angle is lined up pretty well. Just back up until the balls touch and your hitched (well really, really close most of the time).
They are on sale this week at HF
http://www.harborfreightusa.com/usa/itemdisplay/displayItem.do?itemid=95684
If you decide to get them, exercise a little restraint when collapsing the "telescoping antennae" as they can be bent/broken. Also, don't push the antennae completely closed since the ball can be pulled off of some of the units when trying to extend the antennae. (I can't recall whether the HF or the Northern antennae has a metal ball on the end to keep the foam ball in place, but one of the balls is now held on with hot-melt)
Charlie G