If you can get your gear to 20lbs or so there are a number of rear racks that attach at the seatpost. You could combine that with a small backpack and carry quite a load.

Old Man Mountain sells rear racks that would attach at the QR and then you could use small panniers.

You could also use a trailer such as a Bob, but if you are going ultra light that might be overkill.

I was thinking of using the seatpost rack to do some ultralight touring between hostels on my R600, but that trip hasn't materialized yet - should work though if you keep the weight down.

Have fun.