Well I take Klonopin but mostly for sleep! I don't know if this is the best advice but if driving (someone else's driving) gives you so much anxiety, why not crank the AC and curl up with a blanket and sleep through the ride? I always do that on long car trips when I'm not the one driving.

Again not knowing if it gets you sleepy or not. I know Klonopin just knocks me out! I am .5 mg every night and I can't sleep without it. I know I have become a bit dependent on it but it was a hell lot better than Ambien or all those tablets of Trazedone.

Good luck and have a safe trip!