Arkham Horror Across The Dimensions

This blogpost and comments are to help flesh out the inspired idea of KingPut to use two Arkham Horror games to, well, let's just let him describe it (with cleaned up grammar):

...I do have a wacky idea for playing Arkham if we have eight guys that we like that want to play AH. We set up two Arkham boards side and place Kingsport and Dunwich between the two Arkham boards. Four guys play one AH board and four guys play the other board. The dual AH dimension game can be played with one complete set + expansion the only thing we'll need is one extra Arkham board. The Kingsport and Dunwich board are shared by both group. Kingsport will be more active because both groups will be activating it each turn. Each group will have its own big bad, doom tokens, etc.

The advantage of this is that everyone can kind of play together and we can play with expansions. But the game can be played in 3 to 4 hours vs. 6 hours with eight players. 

 That's pretty much all he's got though. I see the narrative as GOOs approach, Arkham shudders and those sensitized to the coming of the GOOs find themselves drawn apart into distinct dimensionally shifted Arkhams--a ploy by the GOOs to keep opponents at bay until they can invade?! 

Whatever--you have two Arkhams.

So far, we've worked out that:

1. Environment/Rumor effects are only in the Arkham that originated them.
2. Effects that apply to "in town" are also limited to the one Arkham.

I was thinking it would be cool if people would return from OW to the OTHER Arkham if possible. It's a hassle to move the player sheet, but come on--that's cool. They become first player next upkeep.

What about a shared Outskirts/Lost In Time & Space?