Finally got round to finishing this off today.
Keeping supply routes open in the latter ones is tough.
Edelweiss was probably the hardest for me. Getting Maikop in 5 turns is very tight. Bombing the unit that occupies it every turn helped; by the time I got there he was down quite a few steps and never swaps for another stronger unit.
Stalingrad was easier than I expected. Piling everything onto the South while just shoring up and threatening in the North seemed to work very well.
Throughout, and particularly in the longer reaching battles the weather played a big role. More than a small amount of rain and it becomes impossible to meet some of the BV turn limits.