Extra Propane tank hauling in hitch basket

Regulations prohibit carrying propane tanks (I'm not sure about cylinders) on a vehicle where they are basically beyond the frame structure--behind the bumper, under the lower frame member, on the roof, or on the front of the vehicle. NFPA regulations prohibit mounting cylinders on RVs on the exterior rear wall or rear bumper, though it's arguable that that probably only applies to manufacturers.

At any rate, it really doesn't seem like a wise idea to me to carry tanks on a hitch mounted cargo carrier, legal or not. I would find some other, more protected way to carry them.