I know you don't want to do too much research (although the nice Tolkien-panel people at Kalamazoo would probably welcome you with open arms), but have you ever glanced through the "Peoples of Middle-Earth" volume The Treason of Isengard? That's where the Rohirrim are introduced, and Tolkien's notes/drafts were not only very specific about a couple of Beowulf borrowings, but also had the doorwardens spouting an entire paragraph of, yes, Old English.

Also, yes, Tolkien is such the big fat thief, but since Peter Jackson was kind enough to include his unsubtle borrowing from "The Wanderer" in TTT movie, we all have something to point our students at and say: "Look! That's an ubi sunt passage!" All the Anglo-Saxonists (OK, the Anglo-Saxonists under age fifty) I know are salivating over the prospect of getting to explain things in terms of the Rohirrim. ;)