Hwy 64 is a good 2 lane road with shoulders. Going that direction, the first half will be a long gradual climb from about 8,000 ft to 10,500 ft at Brazos summit, then back down from 10,500 to about 7,500 ft. Its the 2nd half, going down the other side to Tierra Amarilla that has about 3 switchback horseshoe type curves. With your size rig you might have some trouble keeping it all in your lane on those curves, but traffic is so light on that road that it shouldn't be an issue. You'll be going slow already, on the downhill section, so just time entering the curves when there is no oncoming traffic.
This is a beautiful high country drive in good weather.
Jim
