I just got a bunch of these wound tracker dials. I think they are a much nicer design than the dice from GW.
I already have magnets on the inside of the hull of my planes, from magnetising the stand on. Now I can stick a dial on. I will certainly be sticking magnets on the inside of the hull of future vehicles.
More info on how the flight stands are attached: http://iron-legion.blogspot.co.uk/2015/07/250-magnetising-flying-stand.html
I found the tracker dials on www.ebay.co.uk. Search for "pyrkol wound".