Main thing sleeping in those temps is making sure ya got enough "insulation" under ya. Better to have lots of blankets or whatever UNDER even moreso than over. Yer sleepin in a trailer so the matresses are thin and that's BAD. Yer cold could easily be bronchitis caused by cold from UNDER you. Cut some fir boughs and put em under a blanket under the matress. Smells nice too.