Zack,
Send fellow member Anaro a pm. She seems to have become the guru on Armada towing in a very short time a couple years ago due to all that she learned concerning their Armada, and the tt they started out with. She is the one I referred to in my first reply, just couldn't remember her screen name.
If you decide to change out your Armada, I would suggest skipping the 2500/250's and go for a srw (single rear wheel) 3500/350. The additional payload (over a 2500/250) should cover the weight of the family for some time, leaving a large amount of the payload left for the tt tw, bikes, and a fair amount of firewood.