I just bought a new 5th Wheel. I have had one before and it came with an old hitch (don't recall the brand but it was nothing special). My new 5th wheel has a GVWR of 12,000 lbs - Dry Hitch of 1625....
I don't pin my handle I use a padlock. I lock the brake away cable to the lock.
If you have a B&W 3000 B&W will send free of charge two hard plastic strips to put under each side of the hitch base in the low channel of the bed. This transfers the weight directly to the cross members.
I have read of people closing the handle of their B&W hitch but not pin it or lock it and arrived at their destination without a problem. I would not trust mine to stay closed like that.