Need advice on mounting subs

I'm doing an install for my cousin and need some advice. I'm mounting 2 JL Audio 12W0's in a reverse configuration. The encloser will be part MDF, part fibreglass and covered in bondo for shape. I've never mounted subs in this way before and have some questions before starting.

Are these boxes usually sealed or ported? What is the best way to connect the woofer to the box? Will the angle the back of the sub is facing make a difference like a normal mounted sub? Do I wire the subs in reverse polarity?

Help with any of these questions would be greatly apprieated.

Thanks Mark

I prefer to make sealed enclosures for all my sub boxes ( easier and better frequency response ). The best way to connect the fiberglass top to the box is to use more fiberglass. If you have a hatchback ,face the subwoofers to the rear of the trunk area and if you have a trunk , then you can have them facing up or forward .

the subs will need to be wired in reverse polarity.