these are the dogs nadgers for being handy. i bought one for those trips on your lonesome to stuff wads of gear in.
pocket for fiddly items as well. bungees run through straps on bottom of bag then onto any secure point (rear footrests) on the back of your bike. warp factor doodly and it just doesn't budge.
for extra protection in wet put gear in a bin bag then in the tailpack. job done.
not bad price that