I am a full timer...........
I ran R-13 Insulation in the folowing:
Genrator area ( I have no gen )
Refer area and underneath refer ( have a Frigidaire refer in my rig )
Inside the storage area all sides and inside roof of storage area
Wraped all four of my slides with R-13 and 3/8" reflective insulation the covered them in a tarp ( cut to size ) with velcro
All inside cabinets have the 3/8" reflective insulation.
Wraped all pluming with R-13 insulation including water heater.
Used 2.5" silver insulation tape over slide rubber to eliminate cold air from coming from all 4 slides.
Took inside covers off A/C and put in R-13 and 3/8" reflective insulation inside both A/C units and vent covers( during Winter only )
Used that Duck Windows clear shrink wrap on all of my windows even the big picture window at the real of my 5'er.
Put 40watt light bulb drop lite in storage area to make sure is stays at least 40 degree's in that area.
I have a 10'X40' Black Tarp on top for my 5'er held on with Velcro ( for winter use only.)
I also have a skirt on my 5er
Here is the links for the materials:
Duck Window Kit!: ( I got mine at Wally Word )
Worked for me last Winter!
Hope This helps