I'm not afraid of walking...Back in April I rode up Haleakala (on a proper road bike, and yes, I spent lots of time in the lowest gear) and did a fair amount of walking at the higher elevations.
My current setup is 72 GI (46X17) which I'm thinking is a bit high for me on this route. I have a 42T chainring somewhere in my parts bin that I think I'll install, and have the 17T freewheel available in case the spinning on the descents gets out of control.