Mu2 fits the bill. Single pilot, fast, can haul, mx and acquisition cost cheaper then a king air. More comfortable. Think it would meet your range requirements.
We have a former MU2 owner on this forum. His insight on actual ownership cost would be insightful.
I saw this thread, and my first thought was "An MU-2 would not fit the bill."
In the F model I flew for 500ish hours had about 3k lb useful load. With full fuel, that left you 1k lbs for pilots/cargo. I pretty much always took off with full fuel, and always at max gross since we were packed with dogs. Yes, MX and acquisition is cheaper than a KA. More comfortable? I would never make that claim. It's not a comfortable airplane at all for anyone with any height. I'm 6' and my instructor was about the same height. He said taller pilots developed the "MU-2 neck crink" which I absolutely did. Mitsubishi designed it for the average size Japanese, not America.
Fast, yes. But the needs of cargo and range won't work. The later models had higher useful load and 406 (or 408? I forget, around that point) gallons of fuel. But they also have bigger, thirstier engines, although they have higher ceilings. All I did were long trips. Houston to Massachusetts was a common one, around 1300 nm straight line distance. With routing longest I had was 1400 nm. The plane could always make it with IFR reserves, assuming no alternate required. But it was not with any margin. 1600 nm? Only with very favorable tailwinds. Keep in mind I was always running it at the max efficiency profile, which I tweaked very precisely through my flying of it.
400LS, Merlin IIIB, or Conquest 2 (C441) are the ones that come to my mind for fitting the bill. We had considered going to a Merlin IIIB briefly shutting down Cloud Nine. It would have fit our mission but definitely less support, higher costs, etc.