I would forget the rears. It's only beneficial for rear passengers and otherwise just messes with the staging. I'd spend that money on cable and leads.
In my (non professional) experience, the best way is exactly what you're planning. Decent components up front, ideally powered by a reasonable amp, and a sub/amp. I have tried a number of positions for the components, and found the best way is to keep both woofer and tweeter down in the foot well (if you can build pods) or door corners, pointing at you as much as possible. My Golf (MK4) has them in the standard door position with just the tweeters angled at me on home made brackets and they sound great. The staging is on the dash, surprising considering where the sound is coming from, but it is far better than I expected (also recommended on a forum) and far better than the dash or door mirror cover positions. The further away from your ears they are, the better!
I have Focal components (10 years old from my old Mk2 Golf), Rockford Punch Sub (even older), and a Genesis 4 channel Amp off eBay 2nd hand, sounds better than my old Rockford did, great amps. Well worth the investment considering how long they have lasted.
The mid bass is ok, better builds may help, but I heard most speakers for cars are not designed for sealed boxes anyway. Your biggest problem is the size of door pods in the 'rocco. Might have to build some? I just fitted a set of cheap Alpine 6x4 in our 'rocco, which sound fine... until you start the engine and hit the road, when they really miss the bass. They are running off the head unit amp (also an old old Alpine).
One more thing I noticed. For mid range punch, nothing ever matched a pair of 6 x 9 infinity kappas I had in my mini many years ago. They were bolted straight to the metal shelf at the back (so not great for staging!) and I think the solid surface helps as much as anything. Far better than a floppy door card. I think this is why the Mk4 golf is better than the Mk2, as the speakers bolt to the door metal.
Anyway, sorry for waffling on
![wakey :wakey:](./images/smilies/d_clock.gif)
& good luck