I am having trouble with bsp offset collisions.  Certain topologies can cause this.  For example:

Suppose my bsp compiler chooses f₁ as the first splitting plane.  Then f₄ will be split into a triangle (f_4a) and a square (f_4b).   F₂, f₃, f_4b, f₇ will be "in".  F₆, f_5. f_4a will be "out"

This is a bad bsp tree for collision detection using offset surface.  The decomposition of the object into two convexes (a ramp and a block) will result in discontinuities that an avatar may get stuck on.  

If, however, I chose f_6a as the first splitting plane, I will not have that problem because the ramp-block connection will be part of the same convex.  How do I prevent this (and any generalization of this topology) from being compiled into a bad bsp tree?  

Beveling is not the problem, because you are only supposed to bevel if the angles are acute.  The ramp-block interface is obtuse.  

Thank you.