2 sa 12's on saz 1500d (box ideas)

[lgnmgr]

like the title says im looking at getting 2 sa 12's and going to buy my brother's saz 1500d off of him. going to upgrade electrical first then get the amp up all hooked up and then getting the subs and building an enclosure myself. what i want to know is what size and tuning should the enclosure be? actual usable space for the enclosure is 18" height, 19" depth, 42" width. going in a trunk with a folding rear seat back. just wondering what you would recommend as far as internal volume and a good tuning for these woofers, also aero ports or slot port? thanks