1600 T Rivers

I am trying to obtain my 1600T rivers license and the USCG have been giving me the run around on many issues i am having. cant seem to get any questions answered. My question is is even possible to get a 1600T rivers license by working on harbor tugs. The more i am learning it seems like the USCG is trying to separate harbor tugs into a different license category such as only allowing masters of towing limited licenses. I would like to obtain my 1600T license and would love to have some input on the best route to take.