Hi,
I too have an early 2012 car (chassis 004) You sound like just the expert I need! I therefore really, really appreciate any guidance you can give me.

To start with, I purchased the "used" Mk1 off Chris himself under the Gentlemans agreement that the bracket situation will be problematic and I will therefore need to sort that out myself!

That said it did come with brackets and I have guessed how they fit with the pre-existing holes... I can find no examples on the internet of other bracket setups.

Here is how it I have currently configured it together on my M3W.... https://photos.app.goo.gl/wVxwRLu5gGjBzXLz5

The good....... The three main bolts holding it to the hub + the top bar + attached "L" bracket all seem rock solid
The bad.... The lower long triangle bracket (at the very bottom of the mudguard) wobbles quite a lot (at it lowest point where the single bolt is) . This cause the whole curve of the main mudguard to wobble along its length, even at slow speeds. Currently the wobble is that bad that its almost as if its made out of cardboard, not CF!

I just like to re-iterate that I entered into buying these Mk1's in full knowledge that i may have some cocking around to do, so this is no reflection on Chris (who i could have brought a far more expensive set of Mk2 instead!)