Need help with my enclosure idea...

[samger2]

I have a new idea for my Jeep Cherokee...but I need help with box design.

Let me start with the subs I'll be using. Two of these:

P3SD410
10" Punch P3 4-Ohm DVC Shallow Subwoofer
3.50 in mounting depth
Recommended sealed enclosure:
0.50 cu. ft. (16.42 liters)
Range: 0.40 cu. ft. - 1.0 cu. ft

Here's where I want to put them:

http://i82.photobucket.com/albums/j275/samger2/backrest6.jpg

Into the backrest of my 2000 Jeep Cherokee firing back toward the glass. I want to build a box that will fit inside the backrest and mount to the metal plate and brackets inside the casing.

Here are some pictures of the measurements.

this one is about 42.25 inches
http://i82.photobucket.com/albums/j275/samger2/backrest2.jpg

Top
http://i82.photobucket.com/albums/j275/samger2/backrest3.jpg

Bottom
http://i82.photobucket.com/albums/j275/samger2/backrest4.jpg

Inside
http://i82.photobucket.com/albums/j275/samger2/backrest5.jpg

Side view
http://i82.photobucket.com/albums/j275/samger2/backrest7.jpg

Problem is...I've never built an odd shaped or "truck box" style box before.

So who's willing to help me calculate dimensions?!

:D

[samger2]

Oh...and here's my general thought for a box...make sense?

http://i82.photobucket.com/albums/j275/samger2/wedgebox2.gif

H=19.5 W=40 D1=5.25 D2=4 H2=14...this will yield 1.44 cubic ft...which /2 is .72 cubic ft per speaker.

Thoughts??