The below is from Peck's memoirs (Wagon Boss & Mule Mechanic). Somewhere along this stretch fits better with the mileages in various reports, as to the distance from Ft Gibson. It also makes Blue Mound the more likely candidate as the mound from which Gano spied the hay camp, as opposed to Osage Mound, further north.

My Quartermaster had now acquired another train of 25 six-mule teams, which I put on the road hauling supplies, in company with the Fort Scott trains; but as he had let a hay contract, I found it necessary to fit up my old train with hay frames and put it to hauling hay (under charge of the assistant till Al's return) from the prairie, eight to 12 miles north of Fort Gibson, on the Fort Scott road, the train establishing camp on the nearest hay field, eight miles out.

Our principal hay camp was the farthest one out from Fort Gibson, about 12 miles, on a branch that has since been called Nigger Creek.[See Footnote] The hay-makers at this camp were guarded by two companies of soldiers, one of the 1st Kansas Colored and one of the 2d Kansas Cavalry, all under the command of Captain Barker, of the 2d Kansas. Several other hay camps intervened between "Nigger Creek" and the edge of the timber, four miles north of Gibson.

WAGON-BOSS & MULE MECHANIC
by Robert Morris Peck
Transcribed, Edited, and Forward by Curtis Payne
Page 127-128

Footnote [14]: The creek received its name as a direct result of the battle. In attempting to escape many of the blacks hid in the shallow water of the creek. When discovered by the rebels they were killed on the spot. In 1989 the name of the creek became controversial and was withdrawn from Oklahoma maps. Payne, Curtis., Texas Cannons-Indian Nations.