Still a novice at building boxes, and i have a few people willing to lend me a hand in case. but what would be a good sized box for the whole back seat in a 2008 nissan frontier crew cab. the length is about 54in. from door to door in the back last time i checked i think. And a couple feet between the wall and front seats. was wondering if anybody had any suggestions for how i should build a box for 4 12" Kicker CVRs.