Jake,
As far as I can see, you are also relying on some parts being white such as the skull and (other) bones, in contrast to "so only red and black objects are visible".
But in any case, you may try to have a look at a quite different approach, namely Knockout Group, with the Opacity of the red parts set to 0; this belongs to the Transparency palette.
kphotopage has made an exquisite demonstration here in this recent thread (where the white parts perform the knockout),
https://community.adobe.com/t5/illustrator-discussions/clipping-mask-and-knockout/td-p/14715260
.