Update time, so since day 1 I never really liked using the factory tray to mount the amps, DSP etc. While it was not terribly flimsy, overall it was not that strong and due to the various bumps and such, was very restrictive as to where I could mount anything. Finally started to address that this past weekend...
First up, a cardboard template.
With that done, transferred that over to some 1/2" ply and cut it out.
It's a tight fit, but then I don't want it flopping about. There are 2 factory bolts that I am hoping to utilize in order to bolt it down, likely with some kind of a metal bracket on both sides. I've got some sound deadener and MLV on the way, also have some leftover CCF from the doors, so before it gets mounted I plan to install that beneath the board. I've got some black carpet on the way to cover it with (might have to trim it a little to fit with the carpet on, depends how thick the carpet is) and I am also debating adding sides, although not sure I will.
The other thing that bothered me with the previous installation, the wiring was a mess. OK, it was functional and no one could actually see it, but it was a mess. I am hoping with a blank slate to be able to tidy this up some. Ordered some firewall grommets and am trying to figure out how best to mount everything where I can easily access controls if needed, but also that it looks neat and the wiring is clean. At the moment I have this.
But, not set on it... open to suggestions... There is a space almost directly beneath the Volvo badge that the factory air compressor / fix a flat was, it's deep enough that I think I could put the power / ground distro blocks there and just have those completely hidden.
Eventually, I may also add some lighting and then replace the factory false floor with something with a plexi window / vents or something.
The other update is that I added an Android Auto / Car Play type add on to the factory head unit, while it works well and having access to multiple streaming apps, Google maps is nice. The problem is if I don't have the engine running, the screen shuts off and it also introduced some noise to everything. You can't hear the noise while playing music, but it's there.
So, that's where things stand today.