I have some loose notes about this observer...
He was born 19 May 92 in x. On 16 Sep 16 he was promoted to Lt zS dR.
On 12 Oct 16 he joined the Marine Air Force as he was posted to SFS Holtenau.
On 10 Nov 16 he was posted further to SFS Wiek
auf Rügen. It seems that he was posted back for a few days to Holtenau on 27 Dec 16...
In Jan and early Feb 17 he spent some weeks on the ship "Württemberg"
(an officer must do this sort of duty..)..
After this ship duty he was transferred to the Sonderkommando* within SFS Flensburg
Sometimes during Mar 17 he joined T-Staffel III
(a unit which never reached the front) but probably in early Apr 17 he was posted briefly to FS Apenrade
before he was posted back to SFS Flensburg as Adj
of the Sonderkommando on 13 Apr 17.
It seems that Oppermann stayed in the Flensburg until EOW. However the sonderkommando was dissolved in Apr 18, so I dont knew what function he had after that..
*the Sonderkommando was the "base" unit for the German torpedo
flyers during the War...
Hope it helps a little