I thinks a terra nova laserlight would be OK - you coud get 4 in an emergency and I think that's the idea, and the sleep in gbag too - I don't think there is a stipulation about weight. They allow the 'foil' blizzard packs too which are actually designed for emergency use. GPS can be carried out but they will be sealed at the kit check, I don't know if you would be able to have it switched on during the run but I suspect not. Tea/ juice/ flapjack type things at Snake and they don't half taste good! I'm not sur eabout liquid - to me 1litre seems quite a lot to carry, but I think it woud be a good bet if it was in a bladder. There should be some more info to come yet I think.