I know I’m very late but… I’d love to have a bush flying missions in the game. I used to play Neofly quite a bit but I’d prefer more “bushy” missions.
Might I suggest illegal missions? Never exceed certain altitude. You’d have to go around and stay in the valleys (neofly had this but it was just a never exceed AGL altitude so it wasn’t really hard)
Also: Fishing! Landing and picking up/dropping off passengers in the lakes.
SAR missions are cool to.
I really like your idea of having more stats than mere money and qualifications for planes. Comfort, speed, karma?, reliability, … Should all factor the missions available.
I wist Deadstick - bush flight simulator wasn’t abandoned 
But I’m very intrigued by your idea!