I would like to point out that I hardly think the Golden Chrysanthemums willingly would allow Samura or Kishiro freighters to transport such goods specifically for the construction of a Rheinland Military vessel, especially since said Rheinland Military vessel would almost certainly end up being used against the Red Hessian Army, with whom we recently signed an alliance. Besides, we just plain don't like Samura/Kishiro.
So perhaps there is potential for involving the [GC] and/or blood dragons along the route? Either way, failing that, i'm liable to be using my RHA character anyway XD