You didnt specify if it was a square or round Kicker solo baric. The whole product number would help too, the L7 differs from the L5 in characteristics.

Generally, the Kickers Solo Barics go real loud, bit muddy(low SQ, high SPL), and suited more toward large ported enclosures.

The JL 12W3 is more efficient (less power for more volume) goes loud and reputedly can sound very clean in the right enclosure and works well in a small sealed box. I dont know that you would need 2 of these in your single cab silverado unless you wanna be deaf in the near future? - !unless! - because they would be mounted isobaric (coupled) you could sacrifice the sealed chamber volume in the DB box. Direct coupling (isobaric) effectively halves the required volume as would be used for the 1 driver.
This could save you some room in your cab!
Has anyone else done this?

The DBK box designs are essentially a tuneable 4th order bandpass box, which is somewhere between a sealed and ported boxes for the suited driver characteristics. (talking driver Q's)

I would be leaning toward using the JL woofer.

Other thing; is the Kicker (if a square 12") too big to fit in the DBK212 box?

It's an old school Solo-Baric, figure around '98 or so, still in excellent condition, I use it everyday in a small sealed box in the same truck.

I've downloaded the plans for the DB2 and I've got a some questions for you seasoned builders;

I'm assuming that Panel B is the speaker mount as they're 2 of them and they are slightly larger hole diameter then Panel A, so...I'm assuming the speaker gets mounted in the movable insert on Panel B?  If so, which side of Panel B and which direction should I point the Solo Baric?

Also I'm not planning on doing it yet, unless this box gets moved to my Tahoe, but to clamshell 2 subs, do they both get mounted to the Panel B on the insert? leaving 3/4" between them?  

Does the circle on Panel A need to be sanded very well to promote good air travel?  Should the entire inside be sanded to a very smooth finish? or clear coated even and waxed?  For example the port, should I round the edges?

The other Panel B appears to be mounted to the very bottom of the box, what is the reason for having the circle down there?

Finally, my buddy as a large quantity of 3/4" acrylic available, how would this sound as a Death Box?  Would an entire box made from Acrylic develop odd harmonics?  Anyone tried it before?

Thanks again for the responses, I was assuming the plans would address these sort of issues, as I have read it needs to be perfect to work right, I didn't want to start sanding and rounding, if the box is not designed for that.