I am planning on my first UDS build next month. While I have not been thinking about an insulated one for my first build I have been thinking that if you took a 30 gallon drum and dropped it inside of the 55 gallon drum then you could add insulation between the two. I was further thinking that I might just have to weld intake pipes between the inner and outer drum for the intakes down low. Then just weld on the ball valve on the intake and a removable cap for the other two intakes.
I have not put much more thought into than that... but I think that it might help up here in New England.
My only question would be what type of insulation to use between the two drums.