Thanks, Ron.  Yeah, I'm glad I put the brakes on and made the test mortise.   When I was triaging the too-large mortise, I was amazed to see how much play there was with the plunge mechanism on that Porter Cable base.  I've got a follow-up to post I'll make below on fitting the Festool router.

Steve - I agree.  Even if nothing goes wrong with the test, you at least validate the approach.