harleyman,
The Zepher is/was the top offering from Tiffen. Great coach. Yes you could full time in it.
You posted about an Endeavor in another thread. I don't have an Endeavor but I did have a Diplomat which is the sister of the Endeavor. Both were Monaco products at that time. I wintered over at Ft Leavenworth while I was attending the Army Command and General Staff College in my Diplomat and had no problems.
What you want to find out is if you have heated bays (ie basement heat). Even with those you will still have to take some precautions and think about skirting for the vehicle. Your fridge will have a tough go but their are some work arounds their also. I think it was Kirk (poster on this forum) who had a good write up on what he did. If you have an electric fridge (some folks have replaced the absorption units with those) then forget about the worries with the absorption units.
That engine in the Zepher is bullet proof just like the one in the Endeavor. You most likely have the 4000 series Allison transmission in the Zepher and a 3000 series in Endeavor.
Jeff