I completely understand but finally found a solution after a few years.
Check this out on how to set this up but this will give you complete control on the gap distance. Wish this was a feature built in and gets very complicated. viewtopic.php?f=8&t=12955
This has been discussed before - and I agree.
I could be a little tricky to program, but parts can be run with different layer settings in different processes, the layer height in support should be able to adjust near the contact point to make an absolute distance setting possible.
doing to separate process is working great for me. One for support the other for the model. Just now S3D just annoys me all the time say the processes overlap and again if I want to generate support. So now I have to hit Yes and then No all the time. accidentally hit yes once which you can't see in the preview and had a real mess during the print since support was being double extruded.