We do have double panes in the Tour plus a 2nd furnace for the back bedroom. We camped in 20-degree weather in NC after Thanksgiving and everything was toasty warm. If we camp with our three boys, we sometimes have 'TRIPLE PAINS'!!!
Bubble wrap should help. Any time you can trap air, you have a great insulator.
Thank you for your comments about my c-o-l-d motorhome. We've tried closing the slide at night but in our rig, that covers up one of the heat vents and one of the others is nearly covered. I've read that double pane windows make a big difference. Does your TOUR have them? If we cover our windows with bubble wrap, might that help?