I appreciate your point of view on this -- it takes a bit of courage on my part to advance any sort of claim that Proctors and Hiatts were up the Missouri as early as 1808. And, yes, I did have some McAlister relatives in the bootheel during the New Madrid quakes that started about then, so there is some possibility that family lore got things muddled. It is a fact that Proctors, Hiatts and Kimzeys were in Andrew county around 1850, by way of Iowa, then down, after the purchase of that corner of Missouri from the natives, so, that, too, may have added confusion.
However, there is nothing to have prevented the 1808 move from Kentucky to what became Andrew County, save the courage of those who may have done it. After Lewis and Clark, and probably before, fur traders often ventured a ways up the river, and they had camps/settlements of sorts along the river.