3 issues: Weather. Weather. Weather. I assume you have the Alberta weather in control.
You have to be prepared to lay up if the weather is bad. If you take I-15 you can get nasty weather as far as Las Vegas. If you cut over to US89 and Flagstaff, bad weather can be well south of Flagstaff. If you run US93 through central Nevada, likewise almost to Las Vegas.
I've made the trip from Eastern Washington to Phoenix in a Class A with toad, in weather down to -11F with no particular problems. On the interstates, none of the hills should present a problem.
