Feldgrau is a likely colour too - a green-grey, possibly similar to the German Army uniform (but note WW1 was different from WW2). Quite a few Fokker E types show a similar tone to nearby personnel at least on some part of the airframe - fuselage only, wings only, or both. However, some coarse unbleached linens are quite dark and brown (think 'hemp'). When I get around to my 'E' I'm going for feldgrau, and good old RLM2 is part of this colour group. There are customised or matched feldgrau paints out there though.
Cheers,
GrahamB