I googled "worn rohloff sprocket" and you see a few, some with mileages, but you also see great variation in what constitutes worn
As for 300g, will it be 300g in the form of what you actually need or just the straw that broke the camels back? For an extreme but intelligent take on this look at
http://ultralightcycling.blogspot.co.uk/ Igor took this route originally to reduce equipment breakages.....
For shipping to out of the way places in emergency I would: go to airport, port or major town and find out which carrier has an office there. Pay what they charge for quick delivery addressed to the office and avoid the hassle and backsheesh that comes in the "final mile" to your temporary accomodation.....
Before you go help Robin pay his wages bill. Establish a rapport with some people at Thorn so you have some goodwill to trade on when you need a little extra special help
Pete, did you not have some tweezers in the first aid kit?
Mickeg, beware the Marathon Extreme. I have some and they are essentially a Marathon Supreme type lightweight (thin sidewall) carcass with a heavy draggy tread. Worst of both worlds to some folk and they don't make them no more
Happy shipping
Ian