Be careful what you promise, and I'll be careful what I wish for....
I hope you realise what you are actually doing here, in that making a mod and making a whole new sim from the ground up are like the difference between a sardine and a sperm whale. Financial issues spring to mind first, what game engine will you use? Creating a new engine is not an endeavour achievable through merely wanting it enough. If you use an existing engine, be prepared to sell your own Grandmother to pay for it.
As much as I admire your vision, UBI have made 5 sub sims and let's be honest, they didn't get any of them right and they are a major player in the game development industry. I'm not mocking you (although some definitely will), but I think you should really go away and do some serious homework on the level of expertise, financial backing, and talent to deliver everything you detail in your post. In the flight sim community I've seen people attempt the same thing and after 5-6 years of random, sporadic updates, those titles are still in development with no release date and a plethora of problems to deal with.
Like I said, I admire your vision, but forgive me for being skeptical.
