Where did you net out on this? I'm working on one right now also. Thinking of doing a cold brew for 6/8 hours get double strength coffee flavor then blend down with water and base spriit. Working on adding a little sugar, vanilla and some sort of creme element as well like a lactose or powdered milk. Dont think you would need glycerine as with sugar and lactose you should get a nice body. Been looking around for some solid recipes but I think its that basic. Filtering and sediment on the coffee will be the issue.
We are going to use a light to medium roast (dark roasts come out bitter) - 8 ounces of ground coffee to 8 cups of water.
Let it soak no longer than 12 hours
Mix your sugar and water ratio. Play around with that till its a balanced tasting coffee.
Add your base spirits and then tweak with the flavorings but use sparingly or it destroys the tasty coffee balance.
Let me know where you get to