Again... Size of the map is irrelevant. The real problem is that the enemy only has four active players, and they don't want to fight you; that won't change no matter what the map size is.
You have forgotten the "herding cats" principle.
Tom, Dick, and Harry are playing for for the Knights. Bob, Jim, and John are playing for the Rooks. We'll forget about the Bish for now because they're the Bish
This is these players on a gazillion base map.
"Jim: I'm gonna attack A21! Bob: I'm gonna attack V43: John: I'm going to raid strats."
"Tom: I'm gonna attack P14! Harry: I'm gonna pork the entire Rook front! Dick: I'm gonna shell A147 from the CV!"
So human players need never meet each other, and hardly do meet. It is not even always because players are actively avoiding combat, its simply different people with their own ideas and no central coordination doing their own thing on huge maps.
OTOH, if the entire map consisted of A1 and A2 then a six man battle would be unavoidable.