I am currently in the process of doing this or was complete actually but due to a fire in one of our barns both of my diffusers (an old cracked one and the new fitted one) are burnt to a crisp, along with my btcc rear bumper. My rear tails have melted into a puddle and a load of other parts that such as service bits and pieces and pressed plates that I'd got the night before. We also suffered damage to an old vauxhall firenza shell that was my dads pride and joy
Luckily the actually car wasn't near as the sheds are a few yards away from the house, but I'm still gutted and can't afford to do anything about the car at the minute especially at Christmas . But all will be well soon, it gives the gf plenty of ideas for things to give to santa for me lol
The rear apron won't fit from the FR/
Cupra bumper but if you are after this look you could go the same way I went, like below and just paint it with either textured grey or gloss black, or whatever