On the subject of airfield performance for little airplanes used for charter and RPT.
I haven't been looking at those new regs but my guess is that something will appear thats not too much different from CAO 20.7.1. The factors that Gaunty mentions for FAR 25 also appeared in the old FAR 135 Appendix A (they may have moved to FAR 23 since) and were applicable to small airplanes. Apart from airfield distance there were additional climb weight limitations.