I have been working on a similar business plan too.
the pilatus PC12, while being a a very modern aircraft may not be the best choice. IMO, the Cessna 208 is a much more viable option.
Operating expenses are much less. Secondly, availability of maintainance & spares is an issue. The 208 is a proven eqpt to operate in and out of semi-prepared airstrips. Also the 208 can be very quickly converted into a freighter. In my business plan this was vital, since the 208's could do pax service by day and freighters by night. with the 208's the conversion can be done in under an hour. Also the 208's have an under-floor baggage compartment. Not sure iof the PC12 has that.
Now the downside: the 208 is much slower than the PC12. Avg block speed is just around 160 knots, compared to over 240 knots for the PC12. The 208 also has an image problem in that it is seen here as a"dabba" (flying box). so while it has no problems in a pure freighter use, it may cause trouble to your mktg staff trying to sell pax tickets.
Overall the 208 is an impressive m/c, and i suggest u atlest take a look at it.