When we observed the way the natives travelled, the first thing we noticed was that people never carry anything bigger than an airline carry-on size suitcase. The suitcases are generally hard-sided, and stand upright on omni-directional rollers. People are able to move easily through crowds and wickets because the suitcase is always close by. We've never seen suitcases like this in the States, but we got a couple soft-sided airline style suitcases with extending handles. These fit easily in the overhead luggage racks of most trains. We've travelled for two weeks like this. Including what we wear, we carry six days worth of clothes. This means we've got to do laundry twice. I'll say more about laundry in another post.
Since you are carrying everything, you may have to make more use of coin lockers if you are going to do any sight seeing en route. These are very convenient but we have run into a few issues. Coin-lockers will also be an topic for another post.