You can play with 6 people without much difference than 7. You can set your turns to be short. I played one Friday evening with 30 minute turns, and a four-year game-span. It was quite pleasant. No, we didn't get to the end of the game (we picked a winner on who controlled the most places, I lost by 1 on the final resolved move), but really, when I've played longer games, at some point it becomes apparently who will win but it takes a couple tedious years to bring the game to completion.

As for friendships, I think one has to state clearly at the beginning of the game that one has a strong chance to turn against their allies at some point. It's a feature of the game. There are ways to manage this risk for one's sanity. :)