Mixing static and skeletal meshes?

This was your other suggestion.

It’s still 2 meshes one open. One closed.
Regardless of how you want to spin it.

It’s the same thing as to have 2 meshes - One for the lid and one for the object.

You still cannot bake lights with both meshes in the scene and you are therefore limited to dynamic lighting.

– using a skeletal mesh doesn’t really provide any gain even though it can include the lid and is therefore 1 less drawcall at a base level.

It adds overhead because of it being a skeletal mesh.
And it requires specific light options to light it correctly.

The only sane way to bake the lights is to create 2 levels. One with the object open, one with the object closed. Bake it.
Then load the different levels at runtime.

This was actually done in a few games, but its usually to do “lights on” and “lights off” which is a bit more complex…