I read both your posts and Rick's including back in February.
You omitted in this post the report that he was buried at the pass April 7.
(1) mustered out April 6 is likely died. (2) Yazoo Pass was a big army/navy operation so the steamer was almost certainly a navy vessel. (3) if of any size it would have been docked at a wharf at some town at the time of his death. i.d. the town and you likely have his initial burial place. (4) Rick is correct that it's unlikely his body was returned home but he may have been reburied later by the army and lacks an i.d. (5) Given the circumstances it's possible but unlikely there is a cemetery record from the time of his death. (6) The army did make records (not all published) of bodies (i.d.ed or not) that were moved and were they were moved to. (7) an alternate method could be to find others that died at the same time and place and find where they are buried.