What battery setup should I use?

[Charles Phillips]

Hey, so my issue is that the largest alternator available for my vehicle is 220 amps and I'm not sure if I could fit that and the stock one together. I still have a stock battery too, but I'd like to look into running my 2 SoundQubed Q1-2200.2s at 16v (on 18v charging w/ stepdown modules or original alt running the car portion), but I'm open to considering any setup. This is supposed to be somewhat musical, so I don't expect to draw any more than 400-500 amps total. SQ says rated 1 ohm @ 16v is 2450 watts each, so basically somewhere in the neighborhood of 5000 watts plus mids and highs which I'm considering a 120.4 from some company running off the stock alt. I'd like to have the freedom to play while parked for like an hour or something at 50% volume, but nothing crazy. I've looked all over and I'd really just like an opinion from someone who's done it before because I'm fairly inexperienced,  as I've only studied car audio and home audio for about a year. Thanks in advance! 

PS yes I know this is a crazy project. I'm an engineering student so I'm learning as I go.