Be careful with this... last I heard... once you splice a single wire in that car it voids the warranty.
That said, I'm with everyone else on this. Component in front, coax in the rear and your Rockford Sub.
I'm not too much into the need for a processor since you're accustomed to Pro Audio. You may/may not notice the difference.
A good 5 ch amp that takes Hi-Level input or a hi to low converter and you're in the game.
Even though you have a high budget, I want to share with you what TheWiseOne once shared with me when I switched out from Pro Audio... Start cheap then upgrade. It allows you to appreciate the difference in sound.
In my fielder I had:
Powerbass 6.5 coax
ID 12 sealed
50 rms on each door speaker
500 rms on sub
Sounds like a little bit but it got loud enough to enjoy INside the car.
I say start small. Learn to enjoy the sound of the music and not just the volume.
The deck in my Prius actually has some Time Alignment features so now i've been experiencing what all this hype about "staging" has been. I'm sure mine isn't perfect, but I can't go back now.