Sub box/Port Question

[explosivesound 1]

Just starting my build but I need to know about the box. Ive seen sub up port back sub forward port forward, sub up port up. I assume any combo will work but I want to verify. I want to do sub forward port up. IT would be the same as port forward but the port opening would be up instead of forward. So I guess it would sort of be like an L. Thats the best way I can explain. I need the port firing where the rear deck would be and the sub facing forward. The back of the back seat is being removed and replaced with the box. The sub will face forward in the middle, and on both sides the MDF will be foamed and clothed so two (though small) people can fit in the back seat! I dont really have the room for the port to fire forward like that, so I figured why not port up and remove the rear deck! Any ideas or suggestions?