I took my Charger there 21 years ago (1st pic Cobra car show in Creede, 2nd pic is from road through Spanish Peaks from La Veta to Trinidad). My car was mechanically restored, but wiring, etc was still original. I was on the side of the highway during that trip. Turns out I had the alternator harness routed between the RPM heads and the distributor cap. Somewhere between Del Norte and South Fork it shorted and burned the wire from the alt through the bulkhead connector and back to the starter relay, smoke everywhere! Luckily I brought a big enough wiring kit to tear out the burnt wiring and put in a temp solution. Had to go to back to Del Norte for an alternator at Napa.
I think things would be different 21 years later, not as many parts for our cars at the parts stores as back then. I believe the parts you could get back then were more reliable too. In addition to things listed in the above posts, I'd bring tools/parts to bypass things that might fail. Example: Hole in a brake line or radiator tube? Use needle nose vice grips to bend it over itself and clamp it off.
When my car caught fire, I had the battery cable clamps loose enough to remove quickly by hand, otherwise my car could've burned to the ground. Which brings us to having a fire extinguisher.