Tuneing subs of different sizes, what to use?

i have a dual cab ute( 4 door pickup)
ok, my system is, and im trying to set up for 80% sq and 20% spl

Eclipse avn6000 head unit (5v preout)
2 sets of kicker qs65.2 (tweeter coaxial mounted @+6db)
2x kicker cvt8.4 subs
running off kicker zx700.5
1x kicker cvt12.2 sub
running of kicker zx400.1

I tried the sub behind the rear seat in a sealed box (tried 15 and 22ltr) but to no luck, the sq was bad,
So its now in the tray in a 64ltr ported box to kicker specs (76 x318 x555mm long port) i think 40hz going off winisd (if the volume doesn't include port volume or 36hz if it does at 79.5ltrs)

i currently have hu crossover set to +6db speakers, and sub out at 125hz,
speakers on high pass at 75hz
2x 8" lowpass at 125hz (sealed @ 12ltr ea under rear seat)
12" lowpass at 60hz (64 ltr ported @ 36-40hz in tray)

As my amp has a built in subsonic filter should i re-tune the box of cvt12.2 to 25hz and set amp crossover to 50-60hz, then fit a subsonic filter to the cvt8.4 set at 60hz and crossover set to 125hz then set qs65.2 to 125hz highpass

any help would be nice thanks