Thank you all for the responses. For the first images, which would be inside the wood part?

I hadn't considered a passive radiator. I have seen them, but know very little about them. Do they function in place of a port? The only problem is the only place on the box for it is behind a center console so there's no room

Here are the specs for the box:

I am looking to get 6 months out of this box. I have a wood shop building me a custom box for the truck that fits 2 12's at 5.7 cu in. I don't like to tell people I am doing this, because everyone says it won't fit in a reg cab dodge, but my truck has an ample 15" of space behind the seats- the only bitch is the center console that narrows the area, but i designed the big box so it will fit if i remove the center console when installing. this will take more time to get right, given my shitty woodworking skills, so i am waiting till the fall when it's cooler outside to complete and install. the single 12" is temporary install, and it has a lonely twin that will stay in its box for a while lol.

anyway, i am thinking about a 6" port. although it is lower than the specs (sundown says 40 in^2)

by comparison, the 6" port needs 25" at 32 hz