Well, I guess such a proposition might be considered bizarre, preposterous and unreasonable but it is perfectly feasible. Think wool, think linen ( not cotton ) , think silk. Leather for boots. There is very little difference between 10C & 20C clothing styles - trews, shirts, jackets, skirts, dresses have all been around for a long time, vid The Iceman. But; no zips, no goretex, no "supportive" underwear, nothing more waterproof than raw wool or oiled leather.
Much will depend on your ability and willingness to create authentic garments and to wear them for thirty days. Apart from the silk none of those fabrics washes or dries too easily and the 10C version of deodorant was to stand down-wind.