The Utah route you listed is fine. But just like in Calgary, the weather that time of year is unpredictable. All the roads you list are subject to snow, particularly US 6 through Soldier Summit.
If the Weather Channel and Utah road conditions website say no bad weather, go for it. Have a backup plan if it is a no go.
In the past my route has been SLC-Moab-Farmington-Albuquerque-ElPaso-San Antonio-Corpus Christie. Cold most of the way till San Antonio!
I've holed up at Lakeside RV in Provo a couple of times waiting for better conditions on US6.
