The last of the western military surveys, that of George Wheeler, mapped parts of the Southwest, including the course of the Colorado River. This sheet is dated 1873, and doesnt quite make it to the Grand Wash Cliffs. It makes a nice test of inserting images, since at first, I could only put in the link: Download JPEG2000 image (5768 kilobytes)
Now here it is.
Clicking on it will give a really large, readable version. The map is from the Library of Congress, Geography and Map Division.
It appears that the only marked route across the Canyon is the Sheavwitz Crossing, in the vicinity of Toroweap. An interesting trek, and I wonder if it was more than a one-time event.