If there is any chance you will not be diligent and stand by the valve when you pressure fill your water tanks I would highly recommend that you just "crack" the valve.
That way when you forget and walk away and come back an hour later it will be running out your vent line but at a trickle instead of at full force - which has already redesigned the shape of your water tank.
Of course the same goes for black flush when hooked up to a manifold for flushing. And unless you have the drain open, I would not walk away for any reason doing that.