Dear Wayne,
you may find it interesting that the vessel was a Fleet Auxiliary of the DITHMARSCHEN Class, of which 5 ships were commissioned, namely the DITHMARSCHEN, ALTMARK (later re-nmaed UCKERMARK), ERMLAND, NORDMARK (later re-named WESTERWALD) and FRANKEN. You may be able to find more pictures, if you also google the sister ships. The Altmark was the companion of the GRAF SPEE and had an encounter with HMS COSSACK at Narvik in 1940!
some more info on operational history and technical data may be found under
www.german-navy.deI have not found proper drawings yet, but there is a card board model available of the ALTMARK in 1/250 (including hull), which is very detailed. PE parts for the model are also offered.
Some 1:100 models are in Museums in Hamburg and elsewhere.
Take a look:
I know of at least ONE sailing RC Model in 1:100, check this vid out:
http://www.modell-movies.de/video/Motortankschiff-Altmark/a7beedded4bc30fe22d5The guy must have had some plans...
Cheers,
Lars