4 15's in the Durango

Well I bought 2 more Fusion 15's. they aren't the same model as mine but they are still pretty nice especially for the deal I got on em'! I believe they are the encounter series.
But I need a new box designed.. I'm in no rush because I still have to get some more money for another amp and all the wood.
But I would like to make the whole box double thickness with the subs facing up towards the roof. I'd like to make it all one big box but have the 2 new 15's in the front half of the box sealed, and have the 2 Powerplant 15's in the back half of the box ported.
Would this work okay?
Because the Powerplants are a lot bigger and would over power the other 2.. plus this way I could get the kick down and sound quality of a sealed box and the loudness of a ported?
I'll get dimensions posted here in a bit..
Any Suggestions are welcome!

Thanks,
Lazy Eye