inverter, or DC-DC charger for laptop etc
 

I'm trying to figure out the best solution for power on my bike, I'll be storing and charging a laptop in the backpack strapped on the luggage rack, and maybe a couple small things in the top case(AA/AAA battery charger, camera etc)
I can buy DC-DC chargers that would plug directly into my electrical system, or I can buy a travel charger to convert voltages, and take my AC adaptors.

Going DC-AC-DC seems a bit redundant, and I think I'll frequently be away from good places to charge, so I'm trying to decide for weight etc.
At bare minimum I can have the laptop charger, and the DC charger for the battery system instead, camera can recharge it's battery pack from the AA's in the grip I think, everything else can be charged off the laptop.

Personally I would keep everything at 12v. Can you get a camera charger for that? The 12v charger for mine from Nikon is around £200, the Hahnel one I bought works well, does mains too, is compact and was maybe £40?

If you did take an inverter and then mains chargers I would have thought all of that would be quite bulky?

How good are the expensive solar panels you can get on rucksacks these days? Could you even cover your top box in solar panels, that would be cool :)

Or

Voltaic Solar Powered Messenger Bag

4 watts won't run your laptop but may recharge it?

There is one with a DC in for my little camera for 20$(optio W10), the laptop DC charger is 79.95.
Weight savings: Not a hell of a lot, I'd only save 1 transformer brick.
power savings: This is where I'm hoping the DC-DC system will pay off.
My bike is renowned for a low power stator(CX500) of about 200 watts so I want to load it as little as possible.
I've got an acer timeline X, so draw is 67.5 watts at max draw, 8.2 at idle, but the charger seems to take 150 watts on the AC side.
battery life is about 8 hours, so charging during the day to use in the evening is fine. My GPS can be run off a USB charger, so I'll just have a usb cord that will also charge my ebook/connect the cameras, and a dual usb port plug in for the 12v socket.
My main camera(k7) has a battery grip that accepts AA's, I'll be charging