I have a Reese 16K which I have used now for 14 years. The instructions that came with the hitch instructs you to have the safety latch open but the handle in the closed position. As the king pin enters it pushes the jaws open, the handle will move outward and then as the jaws close the handle snaps back into place. I close the latch, put a pad lock through it and do a pull test. See instructions at this site http://www.reeseprod.com/content/downloads/installation/N30047.pdf
When I bought my first 5th wheel the dealer instructed me to do it this way and I have never had an issue. I always do a pull test after raising the landing gear two inches.