I understand your concern about the basing limit, but as we are five players it would be hard to make a competitive game. The more, the merrier! I'm sure people are fair enough to base at different airports.
The starting plane reflects a startup airline, as it is a re-fitted Convair 580. It is not a bad plane, so I don't understand your concern. The AM economy is very very fast, so it is possible to create an AA-like airline in a few years, even if it's in this world.
If we are going to limit the basing area, it might be good to select an already known area like North America and EU. But again, the more people who join, the more fun it will be!