Hi Tom, As a wildlife management consultant, I have done a fair bit of research into exclusion fencing for roos and deer and have done a few talks on exclusion fencing at Landcare groups etc in NE VIC. Most people are put off by the cost, and haven't gone ahead, but a few farmers and "edge of town" people I know have installed electric fencing on high value crops such as hazelnuts and to protect their gardens from deer and roos, and they all swear the fence is worth the cost because it works 24/7. So I have book learning but no real experience. Perhaps some other farmers have done the hard yards and can share some knowledge?
There seems to be two ways to go, electric and non electric.
Electric. If you are looking at electric, call your local Gallagher rep, they seem to be the market leader in South Eastern Aust where I live. If you have flat or gently undulating country and are looking at a new fence, check out the "Weston Fence" that Gallagher are teamed up with. If you want to upgrade an existing fence, or have uneven or steeper country or can't afford a new fence, talk to Cameron or Brett at High Jump Fencing http://www.highjumpfencing.com.au/products/fence-boot/ they sell a fence heigh extended for steel posts to lift the fence to 1.8m, you can buy the in straigt, left or right bend, and they sell a great inline insulator as well. They also sell the "fence boot" that is an outrigger on the bottom of the fence. This makes the fence look like a "C" shape, and the animals get a shock as they approach the fence, and when they look up to jump they can't see over it. The add ons can go on every second or third standard post so you can save a few dollars there. Best to have a electric fence unit with the highest Joule rating you can but - hit them hard and they soon learn to stay away. Gallgher call this a "memorable" shock but I wasn't game to verify the claimed 100joules! If you use a "fence earth" (rather that a "ground Earth) you wont have earth failures you wont have earth failures. If you have every second wire live the fence will still shock jumping animals that have their feet off the ground (foxes and dogs have learned to jump between the wires so they don't get a shock). Lastly, when you are looking at the Gallagher Weston Fence design, check out how they connect the live and earth wires every few hundred metres so that the current will still flow past a breach in the fence.
Non Electric. These fences mostly use "Feral mesh". The best info source for non electric exclusion fencing is https://www.pestsmart.org.au/tag/exclusion-fencing/ or you can google "Cluster fencing QLD" I have heard several good news stories about this type of fence, but I have not seen it in action to comment.
Hope this was helpful, all the best, Bob