My main concern was would a WDH have a positive effect on a DP. Replies from Ivylog, ScottG, Larrycad, ChrisBryant confirm what I was wondering.
It sounds like a WDH on a DP isn't going to have much effect and may even create a problem. That's probably why I have never seen a WDH on a DP. I will check the hitch for 2 crossbars and if not, have the hitch beefed up.
The trailer empty weighs 3300 lbs so my total towing weight with vehicles and misc. things is around 8000 lbs. My concern was tongue weight due to the axles behind center. Thanks for all the replies.