Add an option that enables stacking elements. I've been telling jacob1 to do that, but he's just ignoring that idea. Why would Jacob ignore that? It seems like a fun idea. Isn't tpt meant to have fun in? Jacob, if you're reading that post, just please, add that option to tpt.
Stacking elements is possible, it's just not supported. That's because stacked elements often do things that only make sense if you actually know what to expect. Otherwise they may even seem buggy. Supporting them would mean someone would have to sanitize stacking behaviour enough to at least make some sense right away, and thus we arrive at the topic of 3D TPT which is another story entirely.
If you need an easy way to stack elements, try to convince someone to make a Lua plugin that stacks elements for you. I'm actually pretty sure there are such plugins out there.
I need that plugin right now.