@Cairo94507 - Michael - I know you're not willing to modify your chassis, but...
Clearly, my firewall isn't quite stock. I had SeatBelt planet make me a set with an extra 14" of length and they work a treat. That said, I wonder if there's a chance we could work up a mount that would allow you to secure the retractor down low, like this.
Note that I'm going to need to do something just like this on the Ferrari build since it'll have some sort of door bar, like my LS car and that passes through the fire wall right where the retractor normally lives.
I'll take a look at the chassis today and let you know what I can come up with.