Can we add a neutral alignment? Unaligned makes sense (Tanarus/Sulis, for example), but I think there is some call for true neutral -- ie Dekk, who is truly centered on maintaining a balance between those two. If you are opposed to this idea, you could put Dekk into the 'Good' column, as he is putting all of his energy into good to reshift the balance away from evil.
HERE IS ANOTHER THOUGHT...
I was thinking we could keep the planes as they are in the 4e world, but the Gods would be unable to leave their demi-planes in physical form. The only exception to this would be the Walker, who can move between the Shadowfell and Elemental Chaos -- hence the name 'The Walker'.
The Walker started as one of the gods in the Shadowfell. He tricked the gods of Evil and Chaos to give them his power, now he travels between the Shadowfell and Elemental Chaos.
The other gods could have their own 'demi-planes' within each plane. So we would have the following (obviously, names would change to more Farlandish types.
Lawful -- Astral Sea
Each one could live on a plane (with their demi-god), the Farlandish versions of Archon, Heaven, Nirvana, Mechalus, etc.
Good - Feywild
Each one could live on a plan, the Farlandish versions on Elysium, Gladshiem, etc.
Bel & Grlarshh would be hiding in small Demi-Planes within the Chaos plane. Bel could live in the Farlandish Demi-plane of Limbo, Grlarshh could live in the demi-plane of the Abyss.... The nature of the Chaos plane has made them impossible to find, although Vornoth is constantly seeking them.
Salystra would live on a demi-plane seperated from the others, unconnected to the planes of the gods.