I have flown the entire 500 and 525 range into and out of many dirt strips...
You are talking - 1050m dirt strip, 1100nm with 300nm alt (in the pacific, you may as well call that 1500nm), I think you might be dreaming... I didn't even get the charts out if you need a definitive answer PM me and I'll email you all the charts (dirt and sealed)
Encore+ (best performer)
Takeoff Distance, Sea Level, ISA, MTOW 3,520 ft 1,073 m
Landing Distance, Sea Level, ISA, MLW 2,770 ft 844 m
Full fuel = 1750nm (useful payload 1000 lbs)
Fuel for = 1500nm (useful payload 1700 lbs)
In a nutshell No chance for 8 pax
King air 350 is the go or Conquest