Hi everyone!
I recently read the documentation about HLODs and methods for collapsing static meshes into a single one, but those meshes are practically generated by the engine, not by an artist. They are perfect to speed up the creation process of a game but let’s say I want to use a custom mesh (custom LOD) for a bunch of actors, or why not, for an entire level, do I need to use blueprints or there is a function of the engine that allows that?
In the attachment there is an example from another game of what I want to achieve.
Thanks in advance! 
Not aware of any built in function. Also this is something I would do manually. Coding in the precise distance at which stuff changes and gets replaced.
When dealing with multiple actors that actually becomes more of a necessity.
Consider using the tags to “group” the items to switch them on/off when appropriate.
Here’s another example I’d like to share:
I know that maybe it could sound a very basic question but is it possible to use multiple tags for a single actor?
You can indeed have several.
Optimization is a balancing act. You probably can re-split the meshes around.
However look into imposters and the plunging by Brucks. These may also come in handy.