Why would linking them together be a difficulty?The options are endless, but linking them together in a coherent fashion is the difficulty.
Universal Creative would not be obliged to feature every single location from the LotR's story, that would be absurd, too much even for an entire theme park. So they select a few iconic locations, and design some world class attractions that sit comfortably inside those spaces. They could easily select three contrasting locations such as Bag End (simple, rustic, homely), Rivendell (otherworldly, elegant, inspiring) and Moria (dark, cavernous, threatening) and have unlimited creative space for rides, attractions, eateries and shops. Two rides, an E-ticket and a family friendly C-ticket; a highly themed full-service restaurant; a counter service cafe; and The Green Dragon Inn for ales but not pipe weed and you'd have Tolkien fans coming from across the the world to visit.
I rather like the look of this scene of elvish beauty, and would very much like to spend some time there:
