[Imp]

The big problem with adding this is as a game feature is I am guessing producing an object that has both the object height and the unit height.
Object height is simple trees to name but one but the unit is always at ground level.
Unit height (ground) things like tall grass snow drifts the unit sits on top at the object height.
The only option would probably be a 2 step option.
1 An object with adjustable height like trees, stone building defensive characteristics and impassable terrain movement characteristics.
2 An object that can be placed in the same hex and adjusts the unit (ground level) height possibly with no icon.
Lot of work really for something that might not work due to unforseen coding entanglements.