The reservations numbers for Havasupai are 928-448-2121 or 448-2141. Keep trying.....
I think its about 35 miles from Ash Fork to Seligman, and that's I-40. From Seligman downtown (as opposed to the outer endge of the Seligman metropolitan area

) it is another 95 miles, give or take to the Hualapai Hilltop trailhead. About 35 of this is on old Route 66, a long flat two lane highway. You can usually see for miles ahead here, but I have no idea if the local smokies have the new K band radar or not....I've never seen one on that road, and we ran most of it between 75 and 80. The posted, er, 'suggestion' as I like to call them, is 65. The last 60 miles is on Indian Route 18, a two lane road which has a number of hills and curves. There are also free ranging cattle along portions of this route, and they have minds -albeit very small ones- of their own. I would allow an hour for this portion, although on the return trip you may be motivated by the need for a cold one and push the envelope a bit. When you get to Hualapai Hilltop, do not attempt to drive farther.
You can save about 50 miles from the Valley by going via Prescott and Chino, but delays on that route will not save any time over the interstate option.
BTW, if you are planning on using the pack mules, you should be at the trailhead by 10:30am at the latest. -Randy