I still question that one, especially after that Apache mock up. The Apache has a tail wheel at the very end of the tail spar like that truck unit had. I now suspect that covered object was the apache model or one like it.
To which I point at the overcast skies of the photos, and state they might have if it was likely to be raining. In either case were both making conjectures.
the rear landing wheel is slightly more aft compared to blackhawk, and the cabin area seems a little longer as well (i.e.: note the under fuselage "bulge" as it leads to the tail, which is more prominent than the Blackhawk family). Different canopy framing too, slight different nose geometry.
I wonder what engines this Z-20 flew with. It'd only be for naught if flew with S-70's engines or those PWC engines, however those use for Z-9 are underpowered for Z-20, same if those use for Z-8...but if the answer is "none of the above", could it be that the new WZ-16 engine is ready?