You can take that 1600T Master supplement test after you receive your 2nd Mate Endorsement it doesnt have to be together. When I upgraded my 2nd Mate’s (new system) in 2006 all I had to have was a valid Flashing Light (with in 1 year). I had some free time a few months later and went down to Charleston and took my 1600T Master exam within the 12months of applying for my 2nd Mate upgrade and they let me sit the next week, as long as my Flashing Light was still within 1 year. That test was 70 questions, with everything for Nav Gen, Safety, Business and Stability. I also had to take Rules again cause I was outside of 1year from taking my previous rules.
SCGamecock, shoot me a PM, curious where your from in SC. Im a Cola native myself.