I have to say I'm with Charles. Humans just have a lot of cultural and behavioural strategies for thermoregulation, many of which are not particularly concerned with energy efficiency. Pretty much all of the solutions you suggest are similarly behavioural and not any sort of re-activation of possible ancestral answers to this problem.
The obvious 're-activation' solution would seem to be for everyone to grow a nice thick winter coat of hair/fur when the weather calls for it. Sadly I think that without some pretty radical advances in the field of genetic engineering this is still science fiction rather than a viable strategy. Even then it would only really be another technological solution. Humans will not genetically evolve a more efficient thermoregulatory strategy until there is a compelling survival advantage to doing so.
I'd be interested to know if you have any comparative thermographs of populations that have historically lived towards the arctic? Do Inuits or Sami improved thermoregulation? If so is it genetic or culturally derived, i.e. by a diet high in fats provided insulation.
TTFN,
WK
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