Rear sag when towing

[Mooreagree]

The only 2 videos I can find on Youtube show significant sag when towing. About to pull the trigger here but this may be a deal breaker. Do the load levelers work - is this normal?

http://m.youtube.com/#/watch?v=m5Pwx1ioHd4&desktop_uri=%2Fwatch%3Fv%3Dm5Pwx1ioHd4

http://m.youtube.com/#/watch?v=r91IzicdNTk&desktop_uri=%2Fwatch%3Fv%3Dr91IzicdNTk