After finally seeing my truck, there are some limiting factors, and as such, I've gone off the deep end and decided to do something I've never done before. Firstly, I knew the area under the rear seat was minimal at best, but I had no idea just how little room there actually was. Secondly, it turns out, I DO have power seats (full power adjustable driver, power lumbar for the passenger), which means the amp under the driver seat is not going to happen.
So, I've decided to build a center console with a sub enclosure and a spot underneath for the amps. Problem solved. Here's my updated parts list, minus the custom box, obviously. I'll write up a build log for that when I start that project.
Head unit: Kenwood DDX574BH
http://www.kenwood.com/usa/car/navigation_multimedia/ddx574bh/
Sub amp: Kicker CXA600.1
http://www.kicker.com/43CXA6001
4 channel amp: Pioneer GM-D8604
http://www.pioneerelectronics.com/PUSA/Car/Amplifiers/GM+Digital+Series/GM-D8604
Front speakers: 2x Sony XS-GS0621
http://www.sony.com/electronics/car-speakers/xs-gs1621
Rear speakers: 2x Alpine SPS-410
http://www.alpine-usa.com/product/view/sps-410
Sub: Rockford Fosgate P3D4-12
http://www.rockfordfosgate.com/products/details/p3d4-12
Sub box: Custom
Backup camera
Price list (in case anybody wants to duplicate). Prices in US dollar, and based on MSRP. If I get the system, I'll put price list for price I actually paid.
Head Unit: $329.99
Sub amp: $250.00
4 channel amp: $220
Front speakers: $119.99
Rear speakers: $80.00
Sub: $250.00
Sub box: TBD
Backup camera: $50
Total: $1299.98 + enclosure materials, taxes, shipping and handling.
I figure the materials for the box shouldn't cost more than $100 including foam and vinyl. I'll try and figure out a way to include some cupholders for the back as well. The only real question I have now is do I make the sub fire down, or fire towards the rear?