Here is an idea:
What if we packaged vessels together and created a single rigid body for each vessel upon launch and disabled everything else (except the mesh renderers and collision meshes for the rest). Then we could only send updates on the location of just that body instead of all the parts separately. We could still interpolate and crudely calculate physics based on some drag value and mass, but we'd only need to approximate between updates. If a collision occurs all we do is enable the components and remove them from being parented to unified body.
