Hey Mip, that's very clever! Unfortunately it did not work in my case.

@Michael, the zero width grooved version seems very handy- the one that produces the trim as a separate object. I can already see me using that, thanks.

I am attaching an example of why I am talking about this. The panel at the bottom right is a grooved inset that looks cool but it was not the intention. I wanted a submerged border around the perimeter. The Outwards option would mean that I would have to do the same treatment to the rest of the object(Impossible in this case), or I would have the panel extruding outside of the initial object boundary.