Use the pegboard as your template/drill guide and overlay it on the stock you plan on using for the base plate.I totally get you, but I’m not sure others do. They aren’t just dog holes, they anre extremely accurate dog holes. Agree 100% you need a jig for repeatable results, otherwise the error multiplies. If pencils and squares were accurate enough Mr. Parf wouldn’t be a millionaire.
A drill guide can be accurate enough if it’s good enough. The only one I’ve seen that measures up is the Rockler and it’s a little pricey, hard to justify for a seldom used jig.
96mm grid isn’t necessary. That’s why I think the pegboard system is the cheapest most accurate way to go. The trick is making a base plate adapter perfectly centered on the bit 😳. Not sure exactly how to do that.