Though one has about 22 spaces to name their ships, and there can be multiple ships with the same name. PS4 only allows the use of your PSN Account ID as a cmdr's name, not to be confused with user name.
I phoned sony, waited almost an hour and was told by a ps4 employee that the only way around the mandatory use of the psn account id usage as a cmdr name, is to assign a sub account to your ps4 which is generaly a feature for your children. AND give permission to purhase ftom the store and if they are the one who purchase's it. Then the name will match the sub account name. Which has to be different than the actual account name. In addition, it must have it's own email AND be under the age of 18. One can choose any birthday they want in the set up process of sub account, no body checks.
IF one has already pre ordered using the actual psn account id, there's no changing it to a sub account order.
The user name should not be confused with the psn account id name nor any sub accounts.