I think any Rivendell would do just fine. OK, maybe a Roadini or a Quickbeam would be a stretch. With the current line-up having longer wheel bases & room for large tires, Clem, Susie, Appaloosa & of course the classic Atlantis (I'm biased that way) would give you a comfortable ride with room for whatever your lightweight bikepacking set up may be.
Seriously, it looks like lightweight bikepacking gear puts less demand on the bike than a full rack & pannier set-up. I know a guy who toured the Pacific Coast on a Homer, with racks'n'bags, and did just fine. Rackless luggage comes in so many configurations there's bound to be some combo that'll hold your stuff & be able to strap on any Rivendell frame.
dougP