"If you can't see the trailer, you can't back up, period. "
I have to disagree...
If you know where the trailer is relative to your tow vehicle and where you want the trailer to go it can be done. But no, it is not much fun and yes, you really want a spotter you can communicate with and trust.
I learned years ago while running boats that if something bad is going to happen it is less bad the slower you are going... "Slow" is your friend. Take your time and practice and it will get easier.
As always... Opinions and YMMV.
:C
