Reverse your reasoning.
What is winter camouflage?
It is mainly white distemper, in order to temporary adjust a standard camouflage a/c to the winter season.
Hence look for a standard pattern 70/71/65 Tante Ju, adapt it with a top layer of white "distemper".
As for tactical colors, that will depend but if it is "Where Eagles Dare" stuff, you'd probably not have any distinctive theatre markings
There are some nice photos of winter camo Ju 52s taken around the Battle of the Bulge, but I can't remember the source (which shows one ditched Ju 52 with and without surrounding snowscape).
But to repeat think 70/71/65 covered with white distemper, not white covered with some color green (or in your case RLM 21 + 70).