6" Aeros arent cheap, but they are worth it. Just buy 2 and quit being a cheap ***.
Ive seen subs up and ports to driver side work great in a ton of ext cab trucks. My buddy had 2 BTL 15s and 2 RF T4ks below the window line in an S10 ext cab and it would do 153 and change on music all day tuned low, to like 30hz. That was sealed on dash. Just subs up and a slot port at the bottom drivers side a couple inches from side wall.
Heres how you get loud: Go to Home Depot/Lowes. Buy a couple sheets of MDF. Start building boxes. When you get a really loud one, leave it in the car. Just build whatever you think will work at first. Listen to it. Note what would make it louder. Maybe less airspace... Maybe more port area... Maybe higher tuning. Make the changes. If you need to at this point, build another box. Repeat.
I dont care what anyone says, its mostly trial and error. Best you can do is an educated guess.