I just did a Venison haunch/leg last night. There is a surprising lack of information out there and what you do find is confusing and misleading. So I had a bone out Australian Red Deer haunch. It weighed just under 2 kg's, about the size of a leg of lamb. The butchers tied the leg with string to keep its shape, I highly recommend this. I cooked it at 54° C for 3.5 hours, this turned out perfectly rare, blood was still leaking red. I'd say your temp range is between 54-57 °C for a nice rare to medium rare result, you don't want to over cook as venison will turn rubbery due to its lack on sinew. When it's finished use a cast iron skillet or BBQ to sear it, I used canola oil in the skillet and seared for around 1 minute, holding it with tongs. In the bag I packed around it butter, sultanas (white grape raisins), sage, garlic powder and generously salted it. I'm telling you it turned out perfect, my wife who said she didn't like venison was on her 2nd piece before I finished my first.