crescendo subs!! new/future build

[bloodline95]

Kind of new to this forum but just wanted to kno anyone cud help me out hear. I was thinkin of getting either 8 forte 15s or 4 contralto 18z and put in a sealed box. I have a Isuzu pup 89 single cab with a camper. Was thinking of jus building a chamber pretty much max out in the camper area, well leaving atleast 10-15inches in the back of the chamber for the batts n amp, and put the sealed box inside the chamber. In a way, its like a 4th order, but im tryin to not to do that. Lmk pepz wat u think and if u don't understand what im tryin to say, lmk. thankz