Weight Distribution bar - using a pipe ... ?

Sorry, but I don't buy that raising the jack is the "only correct" way to do it.
If that were true, then why would the manufactures bother making a pivoting bracket with a nub for the pipe? If they intended everyone to use raise the jack and flip the lever by hand, then they would have simply installed a hook on the frame for you to slip the chain link onto.

There's nothing wrong with using the pipe.