If you are staying in Phoenix for the month of Feb., I suggest doing an overnight or two to the Grand Canyon in your tow vehicle (unless the RV park prohibits leaving your unit for that long.) It's a 4-hour drive. Check the weather forecast for planning.
If you do decide to RV to the Grand Canyon and you don't want to stay overnight in below freezing temps of GC, Williams or Flagstaff, then stay in Sedona/Cottonwood area. It's a 2-hour drive from Sedona. Of course, still check the weather.
But as already mentioned, sunrise and sunset are the most magical times, so an overnight at GC is best.