@wim Nice i like that option. I have done it in the past by coding clipping planes from grid-lines in GH and using a value list, but this keeps it all in Rhino which for some it better.
I guess you code all the saved viewports with there clipping planes in GH if you did not want to make them all manually. Though this could get complicated if you need the Clipping planes at different view angles in perspective for each view. Simple enough in parallel views i would think.