I agree with those saying to hook up to the trailer coupler, pull out to level spot and then hook up the bars. That's the way I always did it for over 40 years. For backing in, just take the bars off before you start.
Dutchman, most WD hitches have a threaded bolt under the hitch head that must be tightened frequently to keep the hitch head from moving down when the WD bars are not tightened up yet or removed. It bears up against the shank portion when tightened down but has a tendency to loosen up with use. I used to check mine before every trip after tensioning the WD bars.
You can see it in the diagram below taken from the Equal-i-zer website manual. Yours must have been missing.
To keep the head from pivoting upward when the WD bars are tensioned, there are washers that go behind the hitch head and hook on to a rod on the top portion that fastens to the shank.
Barney
2004 Sunnybrook Titan 30FKS TT
Hensley "Arrow" 1400# hitch (Sold)
Not towing now.
Former tow vehicles were 2016 Ram 2500 CTD, 2002 Ford F250, 7.3 PSD, 1997 Ram 2500 5.9 gas engine