The basic gist is to pull down the carpet on the hull side, and glue or glass on some stand off blocks. Then you can screw your amp rack (usually marine ply coated with fiberglass resin) into those standoffs. That's how I did it in my vride.
Note that because the rack is mounted off of the hull wall, there is space behind the rack where you can run your wires.
If I were you, I'd forget the additional subs and run the 500.2 to the pro60s and the 300.4 to two pair and the 700.5 to the other pair (bridged?).
The 700.5's ab section (which is the same as a 350.4 if memory serves) will get HOT, especially if you are running it at 2 ohms. Better to give speakers their own separate channels.