Olly, you can put visor cleaning stuff in your pocket.
How?
You do not need the fancy spray bottles of cleaning fluid from HG, or anything like it to rattle around in a cavernous top box.
Get yourself an artificial chamy cloth. Cut off a tidy square, roughly 3" x 3". Put it into a smallish pastic bag. Wet it thoroughly and tip out the water. The cloth will stay wet all day. Got a bit dry? Wet it again. Why artificial? As it's not natural it won't go mouldy or stink. When you come home, rinse it out and leave to dry for a few minutes. It will last you a couple of years. It will also be handy to wipe the dew off your adventure bike, when you have been forced to leave it outside, the biker friendly hotel you chose not saving a heated garage.
To polish? A similar sized square of micro-fibre cloth. Also good for polishing bling. Keep it in another small plastic bag. The truly fastidious can add a cut off toothbrush, to clean out the air vents.
The advantage of putting the two bags in your pocket? When you wander off for your coffee you will probably have your jacket and helmet with you. Undo your jacket pocket at leisure whilst sat chatting to your mates and polish your lid at will. Your mates will gawp open mouthed at your genius.
For anything else, like disc lock, puncture repair kit, you can get a very simple soft bag that hangs under the rear rack. They work fine and do not rattle. No need for a topbx at all.
PS Not related at all, but if you want to put something really useful in your cargo net instead of bottles of visor cleaning spray, get a
http://www.abus.com/eng/Mobile-Secu...ecurity/Locks/Special-locks/Combiflex-Pro-202
Really good. Loop it through a helmet, jacket, the zip of your tankbag or whatever and wander off reasonably comfortable that it will be there when you come back. Easy to use, which means you will use it more often.... And so much better than leaving a helmet dangling on a mirror.
We tend to do it that way in Cheshire 
