I'm aware of the mechanics of relativistic travel. I'm also aware of the terrifying energies that will be bombarding a ship - the interstellar medium is quite cruel to objects that are approaching C.

The amount of shielding this vehicle would require is massive - solid feet of shielding to protect the occupants. So the economies of scale make it obvious: the vehicle would have to be enormous. More of a hollow asteroid than a spaceship. Is there enough energy available to launch that to another system?