Have considered a wooden folding "wind screen"- that would help with the north wind for sure . I did google some "hi tech" spray on insulation and contacted a couple of companies. 2 or 3 were very promising- except the cost was obscene, the application technique was very unforgiving (not very durable, required pristine cleanliness, needed a uv coating, LONG setup before use...etc) I think the best solution is to use it for what it is: A large cooker that can do a TON of food- load it up and it burns as much fuel as it takes- charcoal, wood or both. OR Use tubing, insulation and and skin over it with 16 or 18gauge- it has to help some. Sell it- take what I've learned and start over from scratch- build an insulated vertical with thin steel and 1 to 1-1/2" insulation. I was too hard headed to do that in the beginning- but I can learn from my mistakes.Dirtytires wrote: /snip Even an ez-up with side walls might help.
Another thought, a bit off on the silly side, but could you have it sprayed in bedliner like a truck bed? The material is thick so would offer some insulation and the texture might slow down the wind (on the surface) to decrease heat loss. It would look better than wrapping it in insulation. I don't know that the heat rating is but it be easy to find out.
Other than that, I'd get a Costco membership and ask about pallet discounts.