If I understand uckuki and bobby correctly, I agree. I wouldn't bother with seeding or randomizing the list, just pop people into games in the order they show up. I would open a chat room window, and first persons who pops in and says "I'm ready" gets in. First person who says "I won my game gets popped into a 2nd round game, and so on.
And yes, keep it to 42s and smaller, or maybe 45s and smaller .... no random, and no gargantuan maps. Never mind Hive bomb.... can you imagine getting stuck with First Nations Americas on Speed? Just scrolling up and down to see where your armies are would take most of your five minutes!
Was a lot of fun -- thanks for inviting me!