Cathy, I am currently spending most nights in my camper during my lambing. The nights have been in the low 20's to mid-teens. I have winterized my camper and the thought of undoing that and then doing again was too much of a hassle for me. I am plugged into ele. and run a small ele. cube heater and keep the inside temp in the mid-50's at nite. I use a 5 gallon bucket with a toilet seat for nitely bathroom runs. I have a lite-weight down blanket over my heavy sleeping bag (LL Bean from the early 80's). I sleep in merino wool long johns and turtle neck with heavy wool socks.
The floor gets cold although I have a carpet runner. Last year, I used a couple of old insolite foam sleeping pads on the floor and they worked better (I rolled them too tight when I put them into storage so they just curl up at the present so I haven't messed with them).
Last year i used straw bales around the outside of the Scamp
....this year I am using a landscape soft plastic (weed barrier) around the outside of the bottom of the Scamp
....held in place with a few straw bales. This is for keeping air from flowing so freely and also to keep lambs from crawling under.
I do have a cover over my scamp
, mainly because I am parked close to a black walnut tree, don't know if this helps insulate, just know when the wind blows, it makes noise and often wakes me up. I am not really boon-docking as the house is maybe a 1/2 block away and I take advantage of the amenities it offers during the day. What use to take me 30 minutes or so when I checked on the sheep, now takes me maybe 10 and as a result the body doesn't seem to get as chilled.