Power amp/ Speaker config advice

Hi, I would love to get some advice from you about some cabs I'm building!  I'll tell you my intentions first.  I play an extended range instrument that reaches down to F1 (~43hz) and regular guitar cabinets/amps just don't cut it.  I'm building 2 cabinets each with 2 Eminence Delta 12s and 1 Delta 15, all speakers are 8 ohms.  I'm using a digital rack processor to give the 15s their own amp simulation and the 12s their own so I can tailor their sounds better instead of having one signal for all of them.  I'm wondering what would be the best way to wire them and what kind of power amp setup should I look into?  As you can see I'm currently planning on having 1 power amp to handle the 12s in both cabs and 1 for the 15s.  I figured since the 12s can consume more power than the 15 in each cab it'd be more economical to have one higher power amp for the 12s and one lower power amp for the 15s.  I was also planning on having the 15s power amp run in 8ohm stereo obviously but wiring the 12s into 4ohm pairs (if possible) so i could get the higher power that amps can put out in 4ohms and save myself the money and weight of a larger power amp.  Is this a rational setup or is there anything I should consider?  Also, what size amps should I look into?  The drivers are all rated at 400w rms and it seems manufacturers recommend getting a power amp that can put out twice what the speakers are rated for but 1600w for the 15s and 3200w for the 12s seems like massive overkill in wattage/my wallet.  I want this to be my "final" rig and have no problems shelling out whatever amount I need to to make sure it's top notch so I never find myself in a situation, no matter it's rarity, that I cut myself short.  I'm also not rich though so I want to make sure I don't go farther than I'd ever need.