Many thanks for the input folks.

I hate the idea of having to replace the brand-new DMC hitch for the Uni-Go version, but I will go there if I have to

One other thing I will be looking into is whether I can remove any slack between the receiver bar and the receiver tube (shims maybe?). The DMC hitch itself is very robust. I suspect the receiver bar's slack in the receiver tube is contributing some free play to the wobble.