Marquezfamily,
Welcome to JOF
Question, is your Durango's 620lb maximum trailer tongue weight "include" when using a WDH? If 620lbs is the maximum tongue weight when using a WDH then the 20BH may not be an ideal match unless one has very conservative loading habits.
You might consider taking your Durango to a CAT scale ($9 & 3-minutes) for a weigh-in under loaded conditions (full fuel, passengers, cargo, etc.) would confirm your "available" payload capacity....., thus reducing the guess work. Knowing whether you might be well within, approaching, or exceeding your Durango's payload capacity may influence your thinking.
Subtract the CAT weight from your Durango's specified GVWR..., the remaining weight is your "available" payload capacity to support a TT's "loaded" tongue weight and WDH weight. Payload capacity and/or rear axle weight limits tend to be reached prior to a TV's towing capacity.
The 20BH has a published (website, brochure, etc.) UVW of 4,290lbs...., but a as-shipped UVW closer to 4,400lbs based on the yellow sticker on the side of the TT.
Worst case scenario......; Loading the 20BH to its GVWR of 5,500lbs would represent a recommended 715lb - 825lb (13% - 15%) loaded tongue weight range.
Moderate 20BH loaded scenario: (4,400lbs UVW) + (600lbs cargo) + (50lbs RV dealer, battery, etc.) = 5,050lbs......, 656lb - 757lb (13% - 15%) loaded tongue weight range.
Everyones typical loading habits differ..., some tow with full fresh water tanks, loading for a family, etc...., so these conditions may or may not apply.
I don't mean to over complicate the thought process, but rather provide insight into what's really taking place.
The following link is a recent JOF thread on the Durango that also contains a couple older links that may be of interest.
Durango:
https://www.jaycoowners.com/forums/f...ngo-64849.html
Bob