At the start all players are limited to play with pilots with a bounty less than 100.000 credits, so there is no overkill at the beginning.
These credit figures make sense in-universe, but they might be unnecessarily long to keep track of in game. How do people keep a record of how many credits they have? One thing you could do to partially simplify it would be to knock the 000 at the end off and include a fine print bullet in the rules explaining it.
The credits of the pilots simply replace the credits (or value) of the vessel... and the major "mathematics" are not this way hard. Most money comes from the missionscards, the bounty for the pilots/ships are simply a nice gift.
That doesn't really answer my question. Are people having to keep track of numbers like 15,000, 109,000 and 250,000 dynamically throughout the game? How do they do this?