DavecUK Yep as yrs ago the wife/I operated a full blown Dodge Sprinter with a full coffee ‘lab’ and I had to deal with below freezing temps part of the year. For the van interior I’d use a small electric space heater, which was no problem as the van was always plugged in 24/7 (well except for when in transit, bwahaha) and in the case of a power outage also had a very large whole house generator on the back/frame. For the exposed water lines I used heat ‘tape’ and placed pipe insulation over that and plugged in as needed. Those fixes along with keeping the water tanks as full as possible (90 gallons total) kept anything from ever freezing.