Make fluid mass consistent across different containers

Please make fluid mass (fuel and water) consistent across different types of containers, i.e. add-ons tanks and trailers.  Currently the fuel tank add-on's fuel mass is more than 6 times what it should be, while the Scout fuel carrier trailer barely has any fuel mass (or actually has the correct mass of roughly 1kg/liter), and the maintenance trailer, generator and CAT tanks have zero(!) fuel mass, to name a few examples.  I understand if the devs want to make it difficult to transport fuel, that's fine, but then make fuel heavy across all containers.

I won't go into the illogical design of how a scout fuel carrier trailer can carry half as much fuel as a massive fuel tank add-on, but at least make the fuel in them weigh the same per liter.