Weird War II - Avalon?

[Purezebo]

I've been thinking about running a Weird War II game. Magic is allowed, even out of TL characters given a good enough background.

Anyway I started thinking of campaign ideas. I saw the generic "Crashland behind enemy lines" type campaign and thought: What if they crash landed on Avalon? Of course they wouldn't know, at first, where they were. Probably thinking somewhere in Eastern Europe.

I was thinking of the Isle of Avalon remaining in a mostly medieval TL, with knights and horses and fullplate, etc. Perhaps King Arthur, Morgan le Fay, other knights as well, all lived. Maybe the group of rugged, mostly American soldiers have to convince him to come help, the now almost destroyed, Britain. Maybe he'll send them on quests? Slay a dragon? Find some MacGuffin?

How would you do this? Where would you take the story? What ideas, unique, and entertaining would you implement in such a game? Has it been done before? I'm interested in hearing what you guys can think of, or have to say.