We travel most every week....so the only things we 'pack up' are the items that sit out on counter tops.
Single pane windows......open the shades during full sun.
Then close shades when sun is no longer shining thru window. Some bubble insulation between shades and glass will help retain heat...same for roof vents.
Enclosed under belly helps BUT you need some source of heat to tanks/valves. You may have a duct from furnace. Otherwise......skirting with couple 100W bulbs
Use ceramic space heaters to supplement furnace......still need to run furnace especially IF heat duct goes to enclosed under belly. PROPANE.....see about having a local company set up a 100# bottle....cold temps/high propane usage
Keep your fresh water tank full.....insulate/heat tape your water hose and drain line.
And everybody gets a new warm/toasty sweater.....footsie PJ's.....lap blankets (snuggies) and sheep-lined slippers
Best of luck!