Question regarding heating toy hauler while towing

Well Im pulling with a crew cab f350 dually. The dog used to ride with us in the truck but a 75lb lab continually whining on a 4 hr ride does not work for me. So unfortunatlly for her she now rides in a kennel in the camper without any problems. I was questioning the heat because we are leaving in the evening and not getting to our campground until around 11PM and wanted the camper a little warmer when we arrived.