I'm using a Carradice Camper Longflap with a 24 litre capacity.

I took the loaded RS out for a 50 mile hilly ride last weekend and everything worked nicely, except the gearing is a bit high and I found myself cruising on the larger sprockets and searching for a lower gear on some steep climbs. I had to do them out of the saddle rather than sitting and spinning and a couple of those in quick succession and I could feel it in my legs. So I'll probably replace the 50t ring with a 48 or 46 and go to a 12/28 or a 12/32 rear cassette, although the latter will need a new rear derailleur too. This summer I plan to use the RS set up to "circumnavigate Massachusetts". I'll ride anti-clockwise around the borders, out to Provincetown and take the ferry back to Boston. It's about 450 miles, but I'm never much more than 100 miles from home.