I will be posting pictures of my sound system shortly after it's done but I can show you the box I based my design off of. This box allows for use of the jump seats. It all depends on what your final goal is in power output. What I did was make the box a little taller (can't use jump seats anymore) but I liked the idea of having down firing subs so they are hidden. My final setup is taller and a touch wider and a little more square than that. The big thing I don't like about that box is it lets the sound from the subs flow forward and backwards, you want to direct the sound somehow when making a down firing box. My sound flows towards the front of the truck allowing for more feel when the subs hit. I'm running two 10' kicker cvr's at a 2 ohm load on a PA880 sub amp (500watts RMSx1@2ohms) it's more than enough to fill the truck nicely. I also put an additional panel on top that covers where I mounted my mono amp and 4 channel and once I get the carpet it'll be carpeted too. My goal was to have an amazing sound system that is pretty well disguised while not losing too much storage back there.
So for my full setup I have
Front: DXI6500 component speakers (made 6x8 adapter plates and flush mounted the tweeters in my door)
Sub Amp: PA880
Subs: 2-10" Kicker CVR
I'm a MECP certified installer and worked for a local company here in CO called Drive In Auto Sound until recently due to finding a better job. When I finish it though if I remember to I'll post pictures and can answer questions for you as well.