Apologies for tagging onto this thread with a tangent question.

What's the luggage space situation like on the trains? I've read you can leave larger luggage by the doors. Wanted to confirm that's acceptable and get feedback how safe that is. Or if there are good alternatives like shipping the luggage via takuhaibin in Japan. We're currently targeting to travel from Seoul to Busan in the early evening on a Sunday.

TIA.