On a serious note, I think it is less important to FAIR if a Tapir could pull a chariot, then that a bunch of rubes in Utah who have never seen one could be convinced that it could.
Cureloms were shape shifting tapirs that appeared to be really big to people etching or translating (cough cough) gold plates, but were really small when seen in the wild.
Tapirs. Chariots. It all works if the Nephites were leprauchans.
C'mon people. Use your brains. It's not that hard.
And if all the Nephites were that tiny, that explains a lot of other things too. Of course finding the remains of their civilization is like looking for a needle in a haystack. Makes sense to me.
I keep flashing on the scene in This Is Spinal Tap where the little people are dancing around the 18" stonehenge!!!! Hey FAIR. Turn it up to 11! Ahahahahahahahahaha!!!
I think the problem isn't so much that there weren't animals that are big enough to pull chariots in the Americas. It is that there aren't any that can be domesticated. Moose can very easily be tamed and are more than large enough to pull a cart but they cannot be kept in captivity because they get sick without large quantities of foods that can only be found in the wild. They can't live off of grains like horses can.