Thanks @Lord Maedhros, those are some good ideas..the Rohan Captain is probably the best idea, but as you said, those guys can be hard to come by...
I was thinking about converting either a Rohan Royal Guard on foot or maybe even just a regular plastic Warrior of Rohan, and then (and Tolkien forgive me !) decapitating the Mines of Moria plastic Boromir and/or Aragorn and using those heads with their long hair and beards which would seem to be a great match for the Sons of Eorl mounted profiles.
Thoughts ? A good idea ? Or maybe not a good match physically or looks-wise ? Or is it just too LOTR blasphemous ?