Wow, I really enjoyed those ideas you came up with for Lego sets based on TGE. I was thinking that those are actually possible to make. For instance, there IS a rabbit piece to put on normal minifig heads:
It would look a bit odd, but it's doable. And you can custom-print Lego figures, but it might be a tad pricey. But for a cheaper option you could always just create locations from the books. And then enter them in Lego Ideas or a Lego conference! People make awesome LotR structures all the time, so a Green Ember model wouldn't be a bad idea.