Just an idea, but if it’s really like that (not sure about that yet). If it’s really like building a lot of navy (without a proper transport force) that Germany then just ignores, that fleet is perhaps an ineffective investment, not? Apart from convoying, but you don’t need an overkill for that. If it’s like that the allies could try a different approach, buying stuff that they can do something with.
What if the UK puts a heavy focus on the ME (building from SA and an IC in Egypt or the ME itself). This could put London in a dangerous position later on, so the USA can invest in protecting London to make sure UK can spend most of its income in the ME (once London looks safe), assisting Russia from there.
USA builds that come to mind for this are FTR, STR, SUB. And perhaps a few occasional DD and opportunistic TRS. If Germany gets the hint and leaves London alone, USA can also start channeling FTR + STR into Russia (it is aircraft so it’s flexible), while the subs fullfill a passive-aggressive role: convoying axis shipping. Of course, the downside is that Germany can focus on a 1-front war which is possibly not a good idea… It would all come down to how much economy both sides can channel into Russia. The side who has the economic edge should win it, if the economical underdog doesn’t have a too big initial military advantage.
As an alternative, the USA could just go all-out against Japan, and then start reinforcing Russia from the South West Pacific, once it has secured India, the DEI, and SE Asia. A way to protect London from a late game axis invasion is still needed as well, ofc. Just another thought. But, as far as I’m concerned, an annoying one since this would mean another (K)JF that saves the day. In A&AG40.2, (K)JF seems to be the one limited thing the allies can do, must do even, otherwise they’ll be toast.
And last but not least, if I have a large allied Navy (with or without a lot of TRS) that I cannot do anything with in Europe, I always comfort myself that this will deter a German invasion of London as well and keeps a lot of German forces pinned down in Western Europe, away from Russia.
Trial and error, and if nothing works, place a higher bid.