I was looking at a sealed box on car audio factory. Meets the specs but looking into other options as well. Try here
Chevy Colorado Crew Cab Console Subwoofer Box - Car Audio Factory -

 

this is a little something that i have drawn up that I'd like to do. I dont have exact dimensions of underneath the seat cause im at school and i dont have my truck up here, but id like to do something along these lines.

 

That's something I looked into for a ten or twelve. I'm looking at a blow through just cause I don't wanna deal with the space issue to get good bass. If I could pull the seats I would but my kids like the ride. I've seen a similar box with an 8 L7 on the crew cab set up thread. Looks good and I'm sure the sundown would fit in your design. In a good box they are killer for the size. I've got two in a dodge magnum

 

Liking the concept design on that box but for security reasons it would be nice if the sub wasn't visible yea know. Unfortunate having the crew cab lol but love the space

 

yeah thats what i was thinking. Heres anther drawing i made up, and also gained a little airspace too :thumbup:

 

Excursion is crazy on the sundown, just make enough room for the downfire and I'd call it a day. You got it figured out.

 

Just don't starve the sub. Trust me, had a sa8 b4... beastly sub

 

We put two of these running on 4ohm in a 350Z at a shop I was at for awhile, It sounded amazing!
and yes, the excursion on those things is ridiculous. I'd love to have one!
I think you'd have to go with your second design though..
With the magnet being as huge as it is, I don't think you'd have room with your first.

 

If you do the front faceing design you can angle the sub to get some more depth, I had to do that to fit my 12" Type R in.

 

It wont be the size that will get you itll be the length the port needs to be to get it tuned low enough to sound well. i had 4 sa8 1st gens tho and theyre beastly in the right box on clean power.