Uninsulated offsets work best in warm weather , not so well in the cold
Well the fire in the firebox loses about 50% of the BTU's from the box, so let's try building the fire in the main chamber!
Helps to have a fairly long main chamber, mine is 36 in. ( same as a chargriller Outlaw)
Started a small charcoal fire in a charcoal basket in one end & when going started adding small wood splits.
Temp 300 near fire & 225F at far end.
Temp is low 40's with intermittent mod wind & chugging right along adding a split every 45 min or so.