The first letter that the Wanderer apparently wrote at North Fork Town on Aug. 20, 1859 and published in The Press on Sept. 7, 1859 has just been discovered. It is a long two-page letter mostly about the Indian towns and people visited, but nothing specifically about the Beale bridges, only the four creeks/rivers that they crossed. Wanderer's second letter written on Aug. 22 at North Fork Camp and published on Sept 8 hinted about this first letter, so I just kept looking.
A few lines in this first letter reads:
"Next morning early, we crossed the two Sans Bois--the Little Sans Bois and the Big Sans Bois rivers-- and a halt was called at Emmachias, or Long Town."
A quick guide follows to finding the eight letters at:
Letter Search only 1859 for
Sep. 7 Wanderer
Sep. 8 Creek Nation
Oct. 4 Creek Nation
Oct. 6 Creek Nation
Nov. 1 Little River
Nov. 3 Little River
Nov. 7 Poteau
Nov. 16 35th parallel
Click on Wanderer letter in The Press ,
Click on highlighted column to get Reader