Enclosure Design Help Needed for 3 Sundown X 12's in a Extended Cab Pickup Please!

[max13b2]

I'm needing some help with a new enclosure design to go into an extra cab 2008 Dodge Dakota. I will be running  3 sundown Xv3 12s on 2 JP63s strapped. I currently run 2 Sundown SAv3 12s in 4 cu.ft. net ported box, subs up and port toward the passenger side door, tuned to 32 Hz on 4k watts, and have attached pics of my current enclosure.  
Main problem is that I'm up against some pretty big space constraints and that's where I need some help with some different ideas. 

 

-My max dimensions (leaving ~10" free for the port on the passenger side to discharge into) is:  38" long, 39" tall (with a small taper to allow for the roof sloping in, and 15" deep.  Do I need to go with a triple layer baffle?

 

-My only idea is to do a enclosure very similar to my current one attached, but mount the subs in a sort of wall style setup. My thought was too have the subs facing forward from behind the passenger seat, and if I mount them low enough, it should fit without hitting the back of the seat. This also introduces a large baffle into the design and will need extra bracing. If I need to go with a triple baffle (will I?) , then I'm further reducing my overall depth by .75" since I cannot increase the depth any more. 

 

-how much airspace is required behind the magnet pole vent to the rear of the enclosure? Using a triple baffle, I'm now within 1.5" of the rear wall.

 

-My thoughts on an enclosure / port design mimics the port style in the attached picture of my current enclosure. The port will measures  10" x 12" at the port opening and 35.75" long tuned to 32hz.. I think I will have to turn the port in an L shape inside the box to get that much length.

 

-Modeling in WinISD shows that with power at 9k total, then my port velocity will be 45m/s ! Obviously this is much more than the 25m/s talked about to keep from chuffing. Any ideas here? Also, this is very close to a square port = not good, but I cannot change the width and with a triple baffle, 15"-3" of wood = 12" of port depth, and in order to get the 120 sq.in. required (40sq.in.  per driver) according to Sundown's website, I have to go with a 10" tall port. Should I do a round flared port instead?

 

 Any thoughts or ideas / enclosure help is greatly appreciated! 

 

Once I narrow down a style, then we can start playing with numbers to see if I can get the required 7.5 ft³ net needed with the 120 square inches of port area. I'm open for any questions!

[max13b2]

Anybody have any creative ideas for me or help with any of the questions above?

 

Throw them out there guys, let's here it... 

[max13b2]

After further research, I think I was confusing a square box being a bad ratio with a square port being bad. It looks like a 10x12 port as I am considering should work fine.  Also, I do not have the space to mount a round port, so it will have to be a single slot port, in an "L" shape inside the box to achieve the required length for 31-32Hz tuning I'm after

 

I found this quote from 2013 from JoeX on this forum:

"Height/Width > 9 or Width/Height > 9 would be bad ratios below 6:1 work nice, ratio 1:1 is best (a square port area)."

 

And it is looking more and more like a triple layer baffle is going to be a must in this wall design as the weight of the 3 woofers along with the large area of the baffle warrant extra stiffness, especially for the amount of power I'm throwing at them.

 

Looking for some further help and insight on this and my other questions above please JoeX