Here come the pictures, per request

I had all the equipment here expect the quadlock splitter and subwoofer enclosure transferred from my old car.
I made a bracket out of wood for the DSP and distribution blocks in the rear arch behind the boot carpets. As there are no dials that need to be adjusted on the amplifier, I just have the USB cable come under the carpet so that I can access it. I applied some leftover sound deadening mat to flat surfaces too. Speaker cables run on the right side of the car and 12v on the left. Speaker wiring: MIB output (Quadlock Y-splitter) - DSP in - DSP out - original wiring (Quadlock Y-splitter).
Here is the only picture I could currently find of the speaker wiring. It runs in a loom under the boot carpet, under rear seat and then to the door sill.
Then I started on planning the subwoofer enclosure. Spare wheel has lots of space and by having the subwoofer there, the whole boot can still be used. I made the enclosure so that the boot floor can't be set to the lower position as I couldn't see needing that extra space. Enclosure is made out of 19mm MDF and the ring was made by kerfing the MDF. The box designed and built by me to ~45 L with port tuning of 30 Hz. There is an anchor utilized at the bottom of the box that bolts it to the spare tire mounting point.
I've yet to apply carpet or paint to the enclosure as it is under the floor where it is out of sight for 1 year now

Subwoofer RCA signal is taken from the DSP as it has support for "Sub Out". I have a remote dial for the sub amplifier in the sunglass compartment on the driver side so that I can adjust the sub volume to my needs. Enclosure port breathes from under the boot floor from the left side compartment, where I don't have the plastic divider currently installed. Messy pics as they have been taken during the building process.