I don’t like that because it leaves an obvious void — might be okay with a small endmill though.
I’m hoping to automate the V carving geometry/operation — worst-case is I program it in METAPOST as I’ve done for other files — I am also looking into Maker.js and FreeCAD and creating an extension in Inkscape.
If you’ll let me know the dimensions of the box you’d like to make, the stock thickness, and what you want for a glue/fit allowance I’ll gladly work up a file for you to try cutting.
Alternately, just cut finger joints: