San Augustin Pass just east of Las Cruces near White Sands Missile Range is your only obstacle between Alamogordo and Cruces. The eastern side of the pass (climbing as you're going west) consists of four miles of 3 - 5% and then two miles of 6% (with a 1/2 mile of 4% in the middle). Going down the west side, you'll have 2.5 miles of 6%, a half mile of 4%, then another 1/2 mile of 6%. The remaining four miles are mostly 5% easing to 3% near the bottom. Only you can judge how your rig will handle these grades. I'm comfortable with them in my rig - but it's a different animal. The evening and morning rush hours experience heavy traffic between Las Cruces and the missile range on the east side of the pass.
Rob