Mythvfx If your object is water tight, it should behave as expected, as the "volume fractions" will distribute the mass density only where the embedded surface is inside of the tets.
Large tets, high young's modulus, low poisson's ratio (like 3 or 2) - make sure that you keep your newton's iterations set to 10. You could also consider changing your material type to co-rotational if you don't want the object to deform, as it is slightly quicker to compute than the default StVK and will rotate freely even with low newton iterations.
-jj