Humanity is going to be in for a rough time when they first meet a hostile alien race, I think. Six box launchers and a 10cm railgun per 10,000 tons of hull is not a high economy of force.
I disagree with the naval planners, 38b km range is more than enough for an early warship and I do not see a need for dedicated military tankers anytime soon. This seems like a pet project being rammed through by some admiral with a brother in the sorium business to me.