Need help building a new box

[JRminivan]

I have a small problem with my box, its too big now and need something smaller. We just had a baby boy last week and now I need the back of my van for the stroller so I need to build a new box that is smaller but still can use my two 10" subs. Right now my box is 48" wide X 14" high X 12" deep, I would like to make a smaller one but not sure on how to build the box and still have place for the stroller also. I have 40" high X 16" deep to play with, the stroller is 21" wide. I was thinking of using the 40" high to make the box.

I'm runing 2 X Earthquake dbx10 and a Alpine MRD-M1000 @ 2 ohms so around 1000 watts. I also would like to keep the box vented. Any help would be great. Thanks

Here my set up now.