We have stayed at the Outback caravan park in Tenant Creek a few times and no problems at all. Like at any caravan park don't leave valuables in sight and lock the car and the van at all times if you are away from it or if you are sleeping, simple common sense precautions.
Tennant Creek is quite safe. The real issues are related around intoxicated people yelling and screaming at each other. It is just like a parallel universe when you walk down the street. They are so busy with each other you are totally ignored. Best advice is don't engage in their issues, leave them to sort it out for themselves.
In regard to property safety, don't wander off and leave your car and van unattended with items clearly visible. They will walk.
The caravan parks are fine and so is the town if you give it a chance. Go up to the Memorial Club for a beer and a great meal. Enjoy the place, it is not as bad as portrayed.