If you have mate of towing Nc, with 360 days as mate you can go to 500 master. This is what you need for the relevant STCW at that point. See the pic, you can vpdsd with a letter. Leadership isn’t on the list as its not required until 2017. Ecdis arpa etc you could defer, I wouldn’t bother with ECDIS myself smiling tugs. Idpay the $200 or whatever and just pay a license consultant with all the deadlines pending.