Cotton & Western Mining Inc. (CWRN)

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They allow triple trailers a couple places in the U.S- in the general Arizona-New Mexico-Texas area and up to 52.5 ton by special permit(no bribery involved).
That's why I said earlier it shouldn't be too hard to maximize a 50 ton load when Mexico already allows ca 48.5 ton without any special permit(normal U.S.limit is 40 tons).

But it all depends on what configuration CWRN wants to use for trucking-there are many different possible configurations. They have to consider the most efficient to offload at port.

Somebody else reported there is a system they will have in place to drop off ore into a hopper or something which will automatically load the mineral conveyors(which CWRN bought for the port in exchange for port concessions(e.g reduced loading of barge or ship price)which will fill the 10,000 ton barges in prep for the ship.
One of the 10 largest world ports uses an intermediate barge system like this because that port is only 7 meters deep(in China).

Others have reported laydown yards are available but will not have to be used with this system-I think pesquero has the most info on that and took pictures of those things,which are probably a part of itmd's compilation in the IBOX.