First, thank you all for the comments!
As a purist I also disagree, if it's possible to make a costumized minifig with existing pieces that's what I will do. Altough it's allowed to make and use non-lego-parts. As an example, a while ago at my lug, for a competion you had to make a costumized, new, non existing collectible minifig. I won. With this Hun, which I made with only lego parts.
About the relief, unfortunately I did not have more dark tan plates.
I tried to be as accurate as possible. And because the mounties official hat is tan I used this one!