I believe there is an approved ferry overload for the Series 300 which was used by a well known Californian company for trans Pacific ferry flights. I can't recall the figures but think it was around 15,500 pound TO weight.
In Canada, the DHC6-300 is approved to operate up to 14,400 pounds TO weight on aerial work ice patrols.
I know a -34 powered Series 300 will fly with a 3,000 kg payload - but don't ask me how I know!
10,700 kg TO weight would be suicidal, not to mention very stupid!
Woomera