NIce boat Tripmix.
Tanbark, or even a cotton look would be nice indeed. Graphics would be a personal choice, and boats are of course, personal.
Talk to a sailmaker and see what they can do. My screacher (a mix between a spinaker and a drifter/reacher) has a anti UV film on it that could be colored and such so I'm sure they make stuff for that.
Your fokk is a Jib or Foresail in english by the way.