In v11 the 2.5D Carving finishing allowance is a Z offset, but using it automatically adds a finishing pass so it cannot be used to …prevent over-the-line perimeter cuts when using blunt V-bits (like it can w/ parts, holes and r/l engraving)
In v12 there are both tapered ballnose (radiused tip V-bits) and flat tipped V-bit tool options, i.e. no Z offset required.
Getting accurate to-the-line perimeters with that radiused tip 60 degree V-bit in v11 would require setting Z zero at .40 above the material and adding .40 to the DOC. 60 degree radiused V-bits are easy because the distance between a radiused tip and a pointy tip is the same as the tip radius (whatever it may be). Flat tipped V-bits are generally easier because you can use an Isosceles Triangle Calculator. Related thread: Tool settings for flat tipped v-carve bit - #11 by dalrun (drawing, calculator example is down the page a bit).