LCA is often done in loops i.e. refining your data sources and assumptions according to the results of the previous loop.
Thus I would start with the simpler way of choosing the RoW process for all the way from CN to NO. Then check whether transport has a high contribution to the results and if yes, I would add more detail based on further investigation into transport.
By the way, I don't think selecting either process over the other makes a big difference between the results except your project is specificly about comparing sea freight transport options.