Bear in mind also that a lot of small charter operators dont plan on being small charter operators for ever, a C406 operator in STN and a Bandit operator in SEN a few years ago are now fliteline and Titan (who have just got a 757 I believe). Both Airmed and Centreline have a caravan or 2, Centreline have a Kingair, 5 years from now who knows what you could be flying for them.
Some airlines actively recruit from specific air taxi operators, jumping in a Seneca, single crew, borderline minimas and flying to a snowbound airport in Scandinavia at MTOW would scare the £$$% out of many shiny jet jockey.