Hello. I know for a fact that a marker was obtained for a man from the 7th on the basis of his obit that said he had been with the 7th Tenn. Cav.I would go ahead and try if I were you.
It seems to me that nowadays if you claim such a thing, the government pretty well takes the family at its word. But of course I could be very wrong.
He could have been sent home early as he was already sick, etc. you just never know. Lots of those records are incomplete to say the least.
Linda