I may be one of the few people who only use trackpad with SketchUp. I was quite used to two fingers to “mouse wheel” in or out of the model, but I am ok giving up on that in order to get two finger orbit or pan.
The two finger pinch is more effort than two finger scroll was. I have a suggestion that would take care of the two extreme cases where pinching repeatedly would be annoying:
Make it be that a quick, brief, pinch-in would Zoom Extents, and a quick, brief, pinch-out would Zoom Selection, if there was a selection at the time.