Modding the battle editor

[Barbarian]

This is a bit weird question, but it there a way to mod the battle editor itself, to add more options and buildings available?
I have noticed that all the buildings, settlements and other objects in battle editor are related to one of the factions from RTW vanilla or a mod, and can be seen also in the campaign. But it would be great if it was possible to add more objects and land tiles, or even new kinds of roads, to increase the variety and make the historical battle more exciting. Maybe, put the features from different mods in the editor.

Has anyone tried this? I am sure that there must be a file, from which the editor takes all the features from, I suspect the descr_items.db, but I am not sure.