To Show Datum Level on Axonometric

I was preparing an axonometric drawing which was to be shown to our client regarding the phasing of the building and the levels of the particular floors, which I used to do it in Sketchup (Fig 1)

(Fig 2 - the result i wish to create)






(Fig 1- SU Model)

However the 3d gridline in Revit 2016 does not allow me to create datum level (Fig 2) in Project , So I ended up using 3d Model Text to indicate the level, Alternatively, I could move it to Massing Environment, where the datum level can be shown.

Hopefully, the upcoming version of Revit would allow us the option to show datum level on axonometric in project environment.