I've had a D'Lan hidden hitch on my NB for 13 years. No problems. Are the NCs that much weaker?
The HF 4x4 is plenty big for track days and such. I have a 4x8 like Nails posted that hauled 4 filled ice chests and all my AX stuff to every event for the last couple of years. It hauled a treadmill last weekend, it has hauled fire wood since Christmas, and a ton of lumber over the years. The only problem I have with the 4x8 is it will not fold up if you put a floor on it (poor design). It will tilt for easier loading.
POS has a 4x4 trailer I might sell you.
It has diamond plate aluminum deck, the standard box on the back and posts for tires and wheels. Or I actually own one with all that and a custom air tank mounted underneath with quick disconnect for the air hose.