Teton Pass Wy/ID

I've been down it with a 40' DP. Being an owner of the Mountain Guide, I knew what to expect such as certain curves with 25mph speed limits so don't go charging down hill with a full head of stream. We did fine, but I wouldn't do it without air brakes and a retarder. If your passenger can't handle steep edges, put blinders on them - you look down over the edge to the switchbacks below you.

As for going up, it depends on how your rig handles the heat. I expect August could be warm even though you'll have some elevation.

Bill