I can definitely recommend a swing-arm bag for small stuff.
I bought a cheap one off ebay, just to try, and the quality is definitely 'good enough' to keep on there for as long as it lasts.
Size wise its perfect for various bits, such as wet weather leggings, my disk lock, small tools etc.
I don't even know its where when riding.
Mods so far;
Changed the brick to an oval tail light.
Replaced pillion seat and pegs with luggage rack.
Changed headlight bulb for Philips RacingVision +150% H4.
Changed levers for 7 Click GP Adjustable Levers.
Changed the filler cap bolts to Red.
Added Grip Puppies foam covers.
Added left side swing arm bag made for Harley Sportster XL1200.
Added mesh screen in front of radiator (thanks to JimInOz for howto)
..more to follow..