King Air country....don't even think about taking a jet in and out of such places...
BFLs on any jet for that matter for unimproved runways will be double of what you have available...at least...and to have Cessna calculate those charts for you wil cost more than a C-550 is worth in today's market..
Cessna will have the charts for that type of operation as most C550 in OZ were capable of operating from sod/dirt.