I went through the Settings file, and a few others related to the economy, looking for just this, but couldn’t find it anywhere. I’m sure it won’t be long before a modder figures out where those parameters are hiding.
That said, I find even the “normal” starts a little easy relative to Starfarer (ie, the original campaign where fleets were generally smaller). There is a “Spacer” start that can be enabled in settings.json (relatively close to the top) but I haven’t experimented with it yet, apparently you start with nothing but a shuttle and a mountain of debt... given the cargo hold size, smuggling drugs may be the only way to make a living.