Hummm. Good points. In the old Europe and Pacific, the Axis would take at least 2-3 turns to invade the US, and would by that point likely get their fleet sunk, and be facing a huge ground force to boot.
But with a 1940 setup, the axis can actually get those turns before the US is at war.
Humm. Lend-lease, perhaps? How about, only can build 6 units per turn, and any excess IPC’s are lost. This would encourage building expensive units. Perhaps only 4 of them can be land units? After all, building a fleet was one of the things the US was doing during this time. However, only 1 of them can be a transport.
Additionally, they can build up to 6 (capacity of 9 permitting) British units per turn, using US IPC’s, representing lend-lease. They are moved by the UK players during the UK player’s turn, and always appear in the Eastern US or Western US, and can’t move until the US is at war except to be loaded on a UK or ANZAC transport (during the UK player’s turn), or to be moved to a Canadian territory. They can’t be naval units.
EDIT: The british units have to be land units.