sooo i am gonna pick up a 01 nissan frontier crew cab 4x4

now i am looking for install ideas because space is VERY VERY limited!!!
there is about 4" at the bottom behind the rear seat and no space at the top.
i am still gonna run a outlaw amp and my eq215ti in this thing and at least 1-12" sub.
so my only thoughts are mounting the amp in the roof.....
and maybe the sub in the bed as it has a hard tonneu cover on it, and running a large port into the cab, or maybe cutting the cab open and putting the exposed front of the sub or subs into the cab..
give me some input and ideas please.