The way tanks have been "fitted" in vans for years is a complete joke. Some bolts and spreader plates through a ribbed floor ? All to hold a cage that will stop a plastic water tank exploding. I love the old Ionics videos showing crash tests of flimsy, thin water tanks in IBC's doing exactly what anyone would expect them to do.
I predict modern van/tank systems will become modular. Floor plates to attatch to existing anchor points in van, adjustable anchoring points for tank frames. A lot of this stuff is already partly in existence for other trades and uses.
Now that its a big expense to drop a battery (to fit a tank) you can bet it won't take long for someone to do the math and come up with a much better way.