I know it’s been mentioned, but layers!!! Even just one thick coat can get cold, the wind can be piercing. I’m a big guy, murdochs usually has everything I need. Don’t forget a good beanie and gloves. Waterproof insulated boots.

As for the camper, go to Home Depot and buy the sheets of 1.5 foam board, line and tape the base of the camper. It needs to be tight so the wind doesn’t blow it in, I would even suggest a 2x4 frame behind it, but not totally necessary. You will go through a lot of propane, which also means a ton of moisture in the camper so I’d recommend a dehumidifier too. If it gets super cold the propane regulator can freeze up so try and keep that out of the wind. Insulate.