I, too, fly smaller business/commuter aircraft, and 4 flight crew (all female, though that's a different story) as well as two pilots has always seemed a bit much.
However, by ticking the box for cargo aircraft, I can change the personnel on-board to 2 pilots plus one "observer" (a passenger who's wearing a safety vest and carrying a clipboard). There's no flight crew except the pilots, and no opportunity to change the number of "passengers" (the solitary observer is always there...) The baggage loading/unloading seems unaffected by this change. So, in my simulated world, the plane is on a non-revenue flight, and being checked out by the observer. Works for me.