You might find it more fun to split this into two, 2000pt, 1v1 battles side by side.
2v2 tends to leave one player doing nothing while 2v1 larger combats are resolved.
To keep things moving, you can try to run a part of the battlefield out of sync with the rest. Its easy for the gap in turn numbers to come into play later on though. You also have a mind-share problem with one player pulled between 'time-zones'.
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You could always have a virtual road/bridge/portal connecting the side by side games.
A unit reaching the 'portal' and successfully given an order appears on the other battlefield with command transferred to the other general.
My 2C.
regards
--Hammerskelp