Personally I would:
Ensure that OKW do not get benefit from caches. At the moment OKH can build them and OKW benefit in a way that their faction is not designed to
We have already seen this happen with the Assault Support trucks soon after WFA came out
Implementing this would not affect 1v1 balance at all and make a big difference on 4v4 where OKW don't really have to make hard choices
