should i use two 12's or four?

Ok, so here is what I have right now, for now I want to make use of this equipment and will upgrade as I can. This set up is going into a Chev Suburban which I will build a box for. I have an older Audiobahn A2300Hct amp 2400w rms x1 @ 1ohm, 1200w rms x2 @ 1ohm, cant remember the 2ohm numbers off the top.. Two RF P3's dual 4 ohm 12's currently in a prefabbed Bassworx box with front port tuned to 42hz according to the info I found online And two Alpine type R 12's that are brand new dual 4 ohm. I do have an extra prefabbed ported box with top ports and could throw both boxes in but thought building a properly sized/tuned box would be better. The subs are all rated at 600rms so I know if I run two on this amp bridged at 2400w I will over power them significantly even after factoring voltage drop and wether the amp will actually produce what its rated for. I did get bored lastnight and wire the amp to my P3's in the prefabbed box and put it in my Mercedes s320 trunk bridged to 2400 and even with the sound proof cabin and gas tank between the trunk and back seat it hits pretty hard. The charging system doesnt care for it and the subs probably wont take it long I wouldnt imagine. So in the Burb should I use all four subs wired to the amp at 1200x2 @ 1ohm essentially giving the subs around the rated 600w rms each? Will this be better for the subs, sound better or worse, louder, etc? Also should I build seperate boxes for the two different typs of subs or would they be ok together in a shared box? Sorry for all the questions and as I said I will upgrade this stuff as I can. Also I am adding a second Alt to power a second Battery to run this stuff seperate from the main battery.

make separate boxes for each pair. In each pair both speakers should have there own chamber ported or sealed. They will sound horrible if they are not separated. Each sub is giving the other feedback back and forth wich makes a baffling sound and the bass gets muffled.

give each sub its own airsspace and port it can be one big box as long as there chambered