real free edge border/mask

While working on this massive mapping project, we realized that there was areas of protection convergence where we didn't really need any blending there but could use the free edge at zero width as a hard edge, but it would be OH SO AMAZING if we could create a border to mask output inside of ai, without need to bring in a TGA as a mask ? i dunno, feels a bit far fetched but hen again maybe not?

should be do'able in v8