Scroll down here. They say they make historic bonnets for film and theatre. Maybe thay can do your khaki version:

http://www.houseoflabhran.net/glenga...onnethats.html

The WPG bonnet is a tam o' shanter, not a balmoral per se, but it is the right color:

http://onlinemilitaria.net/shopexd.asp?id=1478&bc=no