The sarsaparilla is easy to do. Just find a store that caters to the folks that like to brew their own beer, and they will have the concentrate and yeast. The biggest expense is the bottles. I like the ones with the captured stopper, but you can get the ones that take a bottle opener.
But here's another thought.
I understand that the Fort wouldn't want people drinking in the barracks. But the Kansas Vigilance Committee just recently purchased a 12X18 wall tent for our new meeting house/theatre/saloon. Think the people at the Fort would let us set up a saloon outside the perimeter? Now, that's what I call authentic!
Grizzle Bear