I took a sidewalk nap once because I was too far gone to carry on. 20 minutes and a can of coke got me back on the bike and I finished the ride. I was way under on the nutrition / drink on the ride. 5900 ft of climbing is a good amount, I did a ride with less climbing and a ton of heat, and I was dying after 2 hours at z3. I was trying to eat and pace out my food during the ride, by the legs just couldn't do it at the end.