I really shouldn't comment on this one as I am a Canadian and didn't have to jump through all the hoops to get mine.
I was driving big rigs before Ontario made it mandatory to have a classified license to do so [1973]. I had a chauffeurs license and upgraded through the Grandfather system to a Class A. I have no endorsement for haz-mat (just a dangerous good certificate)[all that is needed in Ontario] and no endorsement for tanker, although that is my job. My paperwork is legal in the 'States as is my medical. I keep a copy of my current medical with me at all times. I have to take a medical every year to keep my class A license, because I am over 65.
But like I said, I am not really qualified to respond to the OPs' question, as I am Canadian and live in Canada.