Medevac.
A kingair F 90 will outperform all, and you will not need a backup.
Most capable piston, C404
Most expensive to run C404
Dont fool yourself, I spent most my flying life where you are off to, no way in hell I will fly a piston twin there, not even a single turbine, a pressurised 400 series as mentioned will put you in the worst weather you can think of, I flew a air ambulance for many years, Chieftain and E90, the 90 was a bit faster and warmer, but also iced permanently, lightning strikes 4 times a year or more, hail..
If you go tar to tar, the C441 is your best machine bar none, it will outrun a Citation on a 1000 km leg.