Speaker question

Hello people,
Ive recently started to gather the parts needed to make a special sound system that ive been designing.
Its called SoundBox (not that this matters ) and consists of 2 500 watt JBL subwoofers and 4 3 way 270 watt JBL shelf speakers all housed into a 4 foot by 1 foot vinyl covered wooden box. Their is a sub at each end of the box, 2 shelf speakers on the front, and 2 more on the top along with a car head unit. Thats the basics of the build, but my question is, will 2 subwoofers positioned like this inside a box create some sort of problem?
obviously the box would be vented to allow sound to actually be heard from the rear of the speaker.

Any help or tips are greatly appreciated.
Thanks.