Tool path for Contour plots

I am creating contour maps from the TopoMiller site. As always I am putting too much data for the size of the carve.

I am using the McEtcher and adjusting using the spring.

I am getting a 0.020 groove on my current pass, which shows well when alone, but I am over running the paths on steep areas of the topology. I am playing with the spring setting to change the groove width. I have had issues due to material thickness changes where the groove gets very thin.

I would like to find tool paths that are closer than a given groove width.
I currently do this by eye in the Fusion Simulation and measure there.

I can solve this by increasing the Step down ( I am trying to stay with 1 meter contours, river valley relatively flat ) or buying larger acrylic ( which is going to happen ).

I guess I am trying to get better at the prediction side.

Side question:
What is a burn width for a Laser on acrylic ?

Thanks !