Well, it snowed in Edmonton a couple of days ago.
Personally, if my RV is just sitting unoccupied, I don't even think about winterizing until the temperature gets below -5C. If I'm in it and heating, I won't worry until below -10C.
Your 5er has an enclosed underbelly, right? If not, all bets are off.
You would have to go quite a ways south to get significantly warmer weather. Thinking back to my childhood when some Michiganders came south to Canada in July and asked me where the ski hills were. (seriously) Weather doesn't work that way.
