Subsurface does seem to be at the heart of every problem I encounter with hard surface modeling. I did a test render using the bevel shader to make it look like the objects were joined, and it actually looked perfect. Man did I feel gross having geometry just jammed inside of other geometry, though. Let’s call that Plan D.
It’s funny that you mention the sci-fi helmet, as it’s one of the few courses I skipped because I didn’t want to get into sculpting yet. I’ll check it out. I was actually looking at the 2017 advanced course on modeling the motorcycle today and noticed he was effortlessly and crisply cutting into his subd surface and mentioned kind of offhand that the edge split modifier let him get away with that. That is apparently a legacy modifier, as you’re now supposed to customize your normals instead…whatever that means. I suppose I need to get underneath the hood and dive into normals more.
Thanks for your help!