Sounds like you have a good grip on what you want and know what you're doing. Same common sense stuff applies...choose with your ears, experience, and reputation. The bass in the rear deck can work very well as long as you get the right speakers for the job...cdt makes some heavy duty 6.5s that would be perfect for an application like that, just make sure you sound deaden and seal the deck as best you can. Here's a link:
http://www.woofersetc.com/p-5574-m6-...s-drivers.aspx
Some serious 6.5s...12 mm xmax, 30 oz magnets, and 1.5" voice coils...should do the trick and they're on sale!!
I suppose, if you're doing the install yourself you could do it for a grand. My set up for that type of a system as an idea would be;
jl audio 441 clean sweep--200.00
cdt 6.5 comps------------250.00
cdt 6.5 mid/subs---------150.00
RF power t-600 amp------330.00 100x4 @ 4ohms
total---------------------930.00+taxes, shipping, etc..
all on ebay from reputable dealers.