While this isn’t an answer to developing the tool as a plugin, have you looked into Rhino 8 recently and seen if the new section tool/model hatches, etc. work for your purposes? I’ve been using them quite a bit for architecture projects and while the subject differs from your use shown here, the geometry is similar in that it’s comprised of many breps/surfaces contacting each other (walls, doors, windows, etc.)
Anyways, having the ability to dynamically hatch the section cuts and control the boundary edge widths and colors as well covers most needed use cases in my projects.
May be worth checking out on your end prior to starting development on a dedicated plugin.
These posts are little “old” by now but summarize the feature in R8: