[Grady Clay]

Kent & Reed,

Yes, the problem is with the starter/solenoid when hot.
The fix is to replace the starter/solenoid with a Bosch rebuilt unit.
As a corollary, make sure the battery connections & grounds are in perfect condition (including the ground strap at the transmission.
Be sure to tighten (clean?) the red wire at the B+ terminal.
There must be good connections at the yellow wire at the solenoid and ignition switch.

You might get us to organize a ‘pit-stop’ starter replacement at an upcoming overnight stop.
I’m sure there is a Pelican/PCA group on your planned route to help and have the parts ready.

Great trip.
We were ten days in and around Yellowstone and Grand Tetons in July (snow everywhere), including camping in the Bridger N.F. and other.

Drive safely.

Best,
Grady