[ToolmanJohn]

Give this a try, if you haven't already.

Spray the blue ox contact points with WD-40 or similar. Spray the chains, spray the tension crank points. Spray the A-Frame clamps at the trailer frame, and check the WD frame clamp bolt bolts for tightness. Make certain there's plenty of grease in the tension bar pivots.

Spray or lightly grease the inside of the 2 inch receiver, and the shank of the WD tow bar. It definitely can make side to side noise. I use a simple side clamp tensioner to lock out movement side to side.

I've had creaking with my Blue Ox, and it was all related to metal on metal contact points. A spray and it goes away.

 

[ToolmanJohn]

Another test, but it may be difficult to find. Get some 2x2 tubular steel about 5-6 feet long. Use it as a test beam in the hitch, lift, push to stress the receiver, see if you can induce bad noises from the receiver.