You wouldn't be able to fit a mid in that panel, maybe a tweeter but the mid would have to go in the 6x9 opening.
This is what I suggest. Buy your front components and the amps and install and tune them. Then decide after that if you want rear speakers. I really can't understand why you'd spend 400+ dollars on rearfill speakers, when they shouldn't be there in the first place.
The W7 subs are going to cancel out the rear speakers. If you want to use rear speakers you will have to build a sealed baffle so that the air pressure from the two monster JL subs doesn't interfere with the movement of the rear speaker. Also you seem to be into SPL, I gaurentee you you will get better SPL if you leave those speakers out.
I think the main reason why people think they need rear speakers is becasue they haven't experienced a strong front stage. The front speakers don't produce the amount of loudness preffered so they think they need the rear speakers to fill in that lack of output.
Your front speakers will be getting 300 watts rms per side. That is going to be insanely loud. You wouldn't even be able to hear the rear speakers.
Try it without it, then after you've setup everything put in the rear speakers and see how much bass output you will lose and how much distortion there is from the subs.
As for the amps the JL 300/4 will power the tweeters and the dome midrange speakers actively. Meaning one channel of the amp goes to each speaker.
Each channel of the JL 300/2 will power the Midbass in the door.
Each JL 1000/1 will power a sub. So 4 amps in total.
Forget about the rear speakers!!!

Open that rear deck out to let the bass flow through.
And buy a ton of raammat or eDead v1.se. Also look into getting some ensolite foam from Rick, or try to get some thicker closed cell foam off ebay.
This is the foam I'm looking for.
3/8" closed cell neoprene foam rubber. Lay that over the deadener to block road noise frequencies that the raammat doesn't block.
Then on top of the raammat on the inside part of the door, lay another layer of closed cell foam over that, to act as a buffer between the door panel and the door.
If you want go more into deadening use a paint on deadener such as eDead v.3 or Second Skin Spectrum on top of the matting before the closed cell foam and also paint the back of door panels and interior panels. Little overkill, but if you don't mind the extra weight it helps.