Well I moved on slightly with this and basically have been looking at a few ideas, it seems you can get 12-24v to 5v 4A convertors on ebay, which would mean you could use something like a power supply for a laptop which tends to be in that rating. This was approach 1, a single power supply for everything.
Approach 2 was similar but, if you look for USB chargers for cars that go in the cigarette lighter socket, they also work on 12-24v to supply you with a usb outlet (or 2) with upto 2.1amp, I have seen 3amp as well but they are a little more rare. So the 2.1a version isnt really expensive so in my case I figured I could get 3, have 1 for each of my 2 usb hubs and then 1 for the Pi itself, then again use a laptop power supply and have each fused converter fed separately.
