[Daryles]

Ok, I'm against insulating the cabin from the basement as the furnace air return goes through the stairs, the basement and back to the furnace.
It helps keep the pipes from freezing.

By all means insulate the walls and floor (add more reflectex ABOVE the coroplast).
I added two 1" layers of styrofoam board to the floor and walls of the battery compartment (lithium batteries don't like being freezing cold when charging).


Air gaps:
The real problem with heating AND cooling

Look under your frame. There are lots of holes and gaps. This allows cold (or hot, summer time) air into your underbelly and can freeze your pipes.
Use gorilla tape to close off any small openings (hydraulic lines, slide cylinder).
Use aluminum sheeting and cut to fit around the hydraulic jacks. Leave the opening around the propane tanks. They must have ventilation (safety code).
Take down your basement walls, crawl in and close the doors. You will see daylight coming in through all the gaps along the frame.
Look behind the convenience center towards your middle jack. Very large opening where the jack comes through. To close this you will need sheet aluminum cut to fit.
Some have sprayed styrofoam on the inside of the J channel skirt to insulate the frame.
There is a panel under the bottom shelf in the pantry. Behind the panel is the water heater. Again you can see daylight coming in around the edges. This requires fire retardant insulation around the water heater to block out the air gaps.
Under your kitchen island there is a panel covering your plumbing. Take it out and there is a big Triangle gap in the corner. Cut and fit styrofoam to fill the gap tight. Use gorilla tape to seal it in place
Just remember, if your pipes ever freeze, you can put a hair dryer down this hole to put heat into your underbelly to thaw the pipes.
Under the bathroom sink you will also find air gaps where the plumbing goes through the floor.
Remove the drawers closest to the fridge. At the back where the propane and electric wiring come through to the oven, there is a gap in the wall by the fridge. Remember the back of the fridge is vented to the outside. Cold air comes in through this gap. Mine is an RV fridge so I have to be careful because on the other side of that wall is the chimney for the fridge heater. I have to use flame retardant insulation here.
Look up in your hitch pin box, you will see your bedroom closet floor and a hole where your 7 way cable goes through the frame. I taped up the hole and wedged 2" styrofoam board up against the floor.
Look at the inside door frame of the pantry. You will see a gap. This leads to the basement.
Make sure your inside and outside slide seals are good.