This is an idea I'd actually like to work on after FEPS. Basically, a recreation of Homer's "The Odyssey" in FE format. It would actually be quite easy for me to do, as I've read the novel literally a hundred times in my life. Monsters? Check. There's already a nice cyclops animation in FE8 that could be ripped and used. (Oh wait it was already done haha)
Mapping wouldn't be an issue. Battles of epic size are what FE is made for. Maybe on some of the slower parts it'd be hard to keep the fun FE flow going, but I don't think it'd be too hard.