This is why there’s a place in all of the entity structs for a height.

It’s labeled in all entity types in 1.95, but in 1.92 it should be an 8-bit “unknown” right above Movement Type (for NPCs), right above warp number (for warps), and… it seems to be defined properly in 1.92 for signposts. Be careful with triggers though, because 1.92 set it as a halfword; just edit the first half of the halfword to set the height and leave the second half zero (for example, 0300 for height 2).

Nvm, seems like you can just make NPCs start on a "10" transition tile like the player would, and when they move on a 3C tile they actually stay on top.
Somewhat of a workaround I guess, though it seems they can't stand still on 3C tiles.