Marcus lived in Montague Co., TX in a small town called Head of Elm. It is now named Saint Jo, TX. I do not know all of his travels but he did make runs to Sherman, TX & Gainsville, TX. The area was the Northwestern frontier as far as I know. When he froze to death he was near the Red River, the TX side, just across from OK (Indian Terr.)
Family legend has it that he was burried in a field near Head of Elm, Montague Co., TX. The body was never found to my knowledge. A few years ago permission was granted to put up a marker for him in the Head of Elm Cem in Saint Jo, TX, Montague County. We go there ever fall for a family reunion, I have taken pictures of his marker.
Now, a question for you. Who is the "we" you meantion that has spent years etc?