Have you ever seen a herd of stampeding elephants? They run pretty fast, between 10-15MPH. On average they walk about 4.5MPH.But, again: Bantha's are huge. Literally elephant sized huge. And slow. How would that even fit in the land? How would that have a PPH that got over 400 PPH? We're talking something similar to a horse-drawn Main Street carriage ride as a feasible third ride for a land.
I understand the theme and concept, but how could it even be remotely feasible in practice? It just seems like the kind of impractical pie-in-the-sky ideas that pop up with armchair imagineers.
Anyways, I kind of assumed they'd be as wide, tall, and long as a PM car, so basically it'd be two PM car lengths per guest group. The PM only went about 7MPH, so at 4-5MPH its still is fast enough to get plenty of guests through, especially when you have continuous Banta's walking through the land.