Six percent isn't that steep when you are in the Rockies. And you should not be worrying about hot brakes if you have the proper setup. You should be using exhaust brake or engine brake and a low gear. Save the brakes for when you need them, only applying them when your speed goes up beyond where you would like it.
I used to just shudder following cars or RVs with the brake lights on all the way down a hill. Your question is a good one what shows a lack of experience, not unusual. Most people never polish big rig through the mountains. Just do a lot more research and make sure you have a proper setup. Safety safety safety.
'11 Eagle 320RLDS '02 Ford F350 DRW 7.3 PSD
"The world will not be destroyed by those who do evil, but by those who watch and do nothing" - Albert Einstein."