For the rear packs, I would look at the Topeak packs.. I have used a small Topeak seat pack for basic essentials and then have a Topeak Dynapack.. It holds up to 10lbs of gear.. I have the larger DX model but they come in 2 sizes.. Great for short trips..
http://topeak.com/products/Bags/DynaPack
http://topeak.com/products/Bags/DynaPackDX_raincover
http://topeak.com/products/Bags/Aero..._medium_Velcro
list of all there bags..
http://topeak.com/products/Bags?WYSE...teack0ell1uc27