speakers on sub box

I am building a small subwoofer enclosure for my cousin's van that will hold one 10 inch subwoofer, that will be located between the two front seats. It is a 1985 Econoline van, and it only has one 6x9 speaker on the dash, so I was thinking I might build some speaker pods that will located on the subwoofer box. They would have their own air space, but I am wondering if this would be a good idea. This van used to be a delivery van, so it is blocked off from the rear, and the doors are just flush metal. I thought about cutting holes in the doors and mounting the speakers there, but I am hesitant to do so, because I don't really know what or how much room is behind the doors.

i did that in an old 73 dodge reg cab truck i had. put 1 15" sub between the seats the put the 6x9s on top it sounded prity good that way.87 ramcharger eclipse CD5000 2 15" memphis M3 kenwood 900rms mono amps

99 dodge cummins diesel eclipse CD4000 1 12" memphis Mclass 800rms audiobuhn amp