Your humility is refreshing Dave! But the short of it is what JWhitmore posted above. Even more succinctly, those devices simply don't draw much power. I would think even the meekest of charging systems wouldn't have a problem with them. Not to mention, you're just topping off the batteries in the camera and the USB tops out at under an amp for 5 volts (so under 5 watts).
If it was me, I wouldn't even really concern myself too much with the load because it is so small. But one thing I would do is wire it through a relay trigger by switched power, or at least through switched power. That way you don't run down your battery when you park your bike and leave all those electrics still running.