I spent hours on this this morning Coach. I found lots of names of French cargo/merchant ships from WWI but no good pictures. Here’s a good start for you:
http://www.theshipslist.com/ships/lines/french.shtml
http://www.teesbuiltships.co.uk/rayltondixon/aalist.htm
You are probably going to end up having to use a representative example of a WWI cargo ship instead of a named sculpt.
For example:
http://museum.gov.ns.ca/mma/wrecks/wrecks/shipwrecks.asp?ID=3416
Type “typical cargo vessel ww1” under google images and be prepared to spend hours and hours.