I like the idea of having more space for higher stack towers or whatever, but why were the press nuts placed on the bottom plate instead of the sandwich plate as in the previous version?
The point here is that you want the screws to stick out at the top to screw the stack on it. If you don't need the extra space from the v3 version and want to build the frame with a lower center of gravity like you was able in v2, you can't do this without a set of extra M3 nuts.
That's a shame, because this problem would have been very easy to avoid by placing the press nuts also on the sandwich plate. This can be placed either above the base plate or below the base plate and in both cases would allow the screws to protrude upwards and the stack to be fastened without additional tools.