What's a good way to do verticality when using 2D battlemaps like in Roll20?

I like to have dynamic maps for my encounters with lots of depth, interesting terrain and interactable objects. My next session is going to feature a spider using its webs to puppet around dead bodies like marionettes. The spider will be perched up on the ceiling for this.

I've run encounters with monsters that fly and hover, or had players who can climb make their way as high as they can, and every time it gets pretty confusing to visually parse on a flat map. I typically attach an icon to tokens that are up in the air, but I still have to answer clarifying questions about distance and movement every single turn. Is there a better way to do this that you can think of? Thank you!