Take your 820 to a bike shop, (a bigger REI would a good choice for this) put racks and panniers on it and see how it rides.
Try a front lowrider rack, 2 smaller panniers and a big saddle bag in back (Carradice) That will haul 25lbs of gear.
I can't tell you if it will work-- you just have to try it. I wouldn't worry about spending $$$ on a Carradice saddle bag however-- if you ride bikes a lot, you use it.