I am not quite sure what your problem is, but I can try.
I live in a rural area in Norway with alpine mountains. They are not very high, typically 12-1500 m, but with forest reaching only up to 500 m. Hence the peaks experience winter at least half of the year, with temperatures going down to minus 30 C and not much snow cover.
I have found that I do not need any special equipment. PET-tubes have no problem at all, and so far I have not had any problems with lock and lock boxes (polypropylene). Some very tough placed I have put a PET tube inside a lock-and-lock box, but I don't really think that was necessary.
Metal caches, like bison tubes, have proved less useful, because the O-rings have problems with so low temperatures. Most of those I have had to replace.