wtw,
it would take a little more than that, and I think it's selling the LC expedition a bit short.
The Spanish tried a few times and failed miserably.
it took a combination of well supplied, well organized, and a decent diplomatic sense.
IMO, it's rather extraordinary that the LC expedition went so well, so soon after the Louisiana Purchase, and is a large part of the expansionist fever that took hold of the US. Of course, the groundwork had been being laid for at least a decade prior to the expedition, well before the land was part of the US.
The westward movement was a combination of factors, and one of them was this notion of we can do anything, go anywhere. a huge success in the expedition fanned the flames. a bitter disaster wasn't going to put the flames out, but the whole manifest destiny thing would have taken a hit.