I decided to make some for myself after reading your tutorial. I'm letting it sit overnight, but will let you know how it turns out. Thanks!
ETA: Also, I used smooth sumac berries instead of staghorn berries. I believe this should still work.
Staghorn is easiest to identify and the smooth looks much like it only smaller... just be absolutely sure you have the edible kind.
The other word of caution is :
ALL sumacs can produce reactions in sensitive people. While almost everyone is sensitive to poison sumac (which is why we call it poison... I'm just saying.) they are all Rhus genus - relatives of poison ivy (and cahsews and more distantly mangos). So you want to be really conservative with even the non-poison sumacs, start with a minute dose the first time and make sure you aren't especially sensitive.