From the sounds of it, he isn't trying to go King Kong Commando with his Yukon; he want's some depth; a little bit of rolling thunder.
Not a **** Earthquake; stop having boners for the substage.
Some questions that need to be answered by OP are
How much space do you want to have left[better yet any idea how much cubic feet are you willing to give up just on enclosure]? Do you want to keep extra batteries out of your hull? Two 10s will without a doubt give you enough thunder for driving. Budget? Hell, two 8s will leave you room for packing the dogs around, and will give you enough bump for daily driving; assuming you aren't a basshead, even if you are there are beefy 8s.