Steve,
I have always admired your work, as you build unique looking guitars. It will be interesting as to what you decide to do, but permit me to suggest some design possibilities;
An headstock of simple wood, with some breathtaking flamed or fiddleback hardwood off-center sun, using the same principles as the Nichols Celtic guitar headstock, bearing in mind that what I am thinking of is simple representation of the sun similar to the Japenese flag.
3rd Fret, a MOP bird in flight?
At the 12th fret, a simple line drawing of a range of hills/mountains, in MOP, very much like the Takamine??
Then for some reason, the rosette could represent a lake, using the appropriate materials- quilted woods in a tone sympathetic to the colour of water can almost look like the ripples in a lake.
It depends what you want to do- whether you want to defy the boundaries of the fretboard/rosette/ headstock "canvas" and be very literal, like Judy Threet's wonderful work or pared down and subtle.
It all boils down to personal choice, and sometimes simplicity and simple symbolism could give way to more grander design!!
Good luck in your discovery and ability to execute any design you choose to go ahead with.