Doodad Models

Ok so you know how many doodads have a base model with several variations? How do I emulate this with a custom model?
I've made a small edit to the Sunken Ruins Archway(s) and now want to use it as well as the Stock ones without making 3 seperate doodads (i.e. 1 doodad with 3 variations).

It's a load of entirely separate models, united by a naming convention in WE.

HOWEVER, from my experience, the system of variations doesn't work in the doodad editor -- only for destructibles.

Anyway, the system is:

path\doodad0.mdx
path\doodad1.mdx
path\doodad2.mdx
...

In the object editor, one would set the model to:
path\doodad.mdx

This won't load, obviously because it doesn't exist. However, setting the number of variations property will (well, should, as I said earlier, it doesn't quite seem to work) make each variation take the appropriately suffixed model.

Luckily for me the sunken ruins arch has a 45 degree variation for it so I just replaced the Doodads\Ruins\Structures\RuinsArchway45_\RuinsArchway45_X.mdx models with my custom one.
It's still very lame that you cannot make your own Base models =/