We like to make things more difficult than they actually are. I suppose it helps retailers sell us stuff, and it helps us charge people more for what we make. :-)
I made a bunch of molding for an on-site project by screwing the router directly underneath a melamine table top, and running a bit straight up to cut the hole. I screwed my fences, bit guard, hold downs, and feather boards right down to the melamine.
Very low tech and ghetto, but it produced perfect result.
And yes, I will tell you that with a couple of pattern/rabbet bits and some wood scraps, you can make a perfectly matching insert using a technique similar to this...