Have you checked the Naval Academy to see if they have any images?

Also, you might advise the Alumni Association or Library, that his entry in the Register of Alumni, class of 1855, is incorrect listing his death as 03 JUN '63, nor does it note his affiliation with the Confederate States Navy.

His entry reads:

Pelot, Thomas Postell, SC A-SC, RES 11 JAN '61 LT KIA in Civil War 03 JUN '63 - Attack on Water Witch Ossabow Sound
[Born in SC, appointed from SC, RES - Resigned USN]