The_Dead_Cow
Mike
The issue with 11.5" square is that you need a BIG spacer. You would have to run the R hubs (long studs) to get it to work. I don't think ARPs would be long enough.
I stuck another 10mm spacer on top of my 28mm that I run on my 19x11" square setup to see how they looked. The suspension wasn't settled in the photo.
Your original post got me thinking about this fitment. OP mustang has replacement "R" studs that will handle IIRC up to 2" spacers. The downside to this setup is tire options as I've only found SC2, A7/R7, & Pirelli slicks.