Hi Peter,
my 2 cents, SPL config setup is done only after performing analysis of how the data is/will be entered already. If the business partner data is being entered in Name 3 and Name_CO, the system always will be creating search terms for the BP by including every data entered under the overall Name field (looks for Name, Name1, Name 2, Name 3 and Name_CO). GTS being just a receiver of master data, in this case the better option rather than introducing a custom code of any kind would be to assess if you want to stop populating the data in Name 3 and Name_CO fields in the source system.
I don't think the config provided flexibility for ignoring any fields.
Hope this helps!
-Shrini