KAT
Just appeared in the Wichita Eagle, Monday, August 13, 2001: "WSU PUTS HUNDREDS OF MAPS ONLINE

Wichita State University Libraries' Department of Special Collections is pleased to present over 325 digitized Kansas maps, dating from 1556 to 1900, for interactive viewing.

I don't find anything to contradict the earlier conclusion that there was no special name for the trail you were trying to identify, but you might be interested in seeing some of the information that was available to travelers at the time your ancestors made their trip.

The maps do cover quite a bit of territory that is far outside what we now know as Kansas.

Instructions on the site indicate that working with these maps would be easier with JAVA engaged, although I didn't try it that way. A couple that seemed, on quick-look, to show the area of interest are at:

Map of an exploring expedition to the Rocky Mountains in the 1842 and to Oregon & north California in the years 1843-44, Published 1845
Described as "First published map to show the entire area west of the Mississippi as seen by a single party. Includes topographic features. Indicates locations of forts.Indicates Native American inhabitation. Has scale at top of map which shows height of mountains including Rockies, Cascades and Sierra Nevadas. Call Number: 1845-0003"

A new map of Texas, Oregon and California with the regions adjoining, compiled from the most recent authorities, 1846
Described as: "Includes topographic features. Indicates the locations of forts. Shows the trails and routes identified as the Great Spanish Trail from P. Angelos (Pueblo de los Angelos, now Los Angeles) to Santa Fe, Lewis and Clarkes (sic) route and Frémont's route. Indicates Native American inhabitation. Designates Oregon Trail as Oregon route on map and Emigrant Route from Missouri to Oregon in table of distances. Identifies Santa Fe Trail as Caravan route to Santa Fe. Call Number: 1846-0002."

I don't see a mention of it on the site, but the newspaper article indicates that:
"Full color copies of the digital maps can be ordered from the Department of Special Collections by mail, fax, or e-mail. It takes three to six weeks to complete an order.
For more information, contact Mike Kelly at Wichita State University Libraries, Department of Special Collections, 1845 N. Fairmount Ave, Wichita, KS 67260-0068; by fax at (316) 978-3048; or by e-mail at michael.kelly@wichita.edu."

John