It would be nice to have dynamic extrusion widths for not only single extrusions, but for perimeters, as well. You can see in the attached picture, there are gaps on the outside of the loops between perimeters, while in the middle, the overlap is more than necessary.
Have you tried changing Edit Process Settings > Advanced tab > Internal Thin Wall Type to "Allow single extrusions"? I think that would most likely fill those small gaps in the middle.
I know S3D will already use single extrusions for an entire perimeter. For example, I recently printed a 0.5mm thick hollow walled part, and S3D used a single perimeter all the way around. It even adjusted the thickness slightly in areas where it was more like 0.6mm thick when it was joining up to another surface.