At some point the definition needs to be freed up from any UV relationship, especially if there are trims on the surface or a polysurfaces where UV is not predictable. In this case you have both.
In that case I use PanelingTools and create a series of sections around the object intersecting planes or whatever gives the spacing you want. You may even want to filter what is interior and what is on boundary. Because many times the logic is different at the boundary.
Many times intersecting the untrimmed version of will give a regular count and spacing, then come back and use only the points that are inside the trim. PanelingTools can help with that too.
UV is very limiting and has very little to do with 3d space or spacing. All to often we try to idealize UV to make sections and spacing to match, but that is very fragile. That is why PanelingTools has more tools beyond UV.
Here are a bunch of tutorials on it: PanelingTools Tutorials [McNeel Wiki]
