Maximum external dimensions are 46" long by 14" deep by 16" tall.
I believe it would be tuned to 32hz with the port 25" long and having 43"^2 of cross area.
Hopefully some fibrefill and possibly inverse mounting the subs will lower the tuning frequency a bit.

Here are my questions:

1) Should I have the vent on axis with the subs? The subs will be rear firing in my trunk behind the backseats.

2) Should I use the snaking vent in the example or a L vent which runs along the back wall?

3) Is there any benift to having two 1.5" vents on each side, as opposed to a single 3" vent, if the tuning frequency remains the same?

4) Will the 15Hz subsonic filter on my amp be sufficent protection against driver unloading or do I have to raise it to 30Hz?

Any other suggestions are also appreciated.