The distance between Lower Crabtree and Lower Rock Creek is 5.5 miles, with Guyot Pass the high point. Guyout creek is the only place to get water, but you are right, in 2012, 13 and 14, I had trouble getting water there in September because of the drought. This year is closer to normal which should help.
But keep in mind that if you are headed south, when you get to Guyot Creek, it's downhill to Lower Rock Creek, about 1.5 to 2 miles distance.
paul