In my club we do many things to make sure the fox is not stolen / thought it was a bomb / hide it. Here are a few things.
Our main fox is inside one of those old surplus 50 cal. ammo cans. It is pretty large making it very visible. A good thing about though is it is (custom) painted with a camo pattern that fits our area quite nicely. We also have someone ALWAYS watching it from a good distance away. Lastly on the actual fox we have a printed paper telling what it is, that it is being watched, and basically a warning telling people to not touch it. On the fox we have a BNC connector. Not sure if your fox is a soldered antenna or just connected via some type of RF connector but if it is consider getting a (if you use a bnc connector) BNC to BNC "extension" cable. This will help with signal tremendously and add many options to how / where you can hide it. Also another antenna trick would be using some type of directional antenna pointing at a metal / RF reflective object. This will scatter the signal and make it look like it is coming from somewhere else.
Now to the actual hiding.. The best place for a ammo can is deep in brushes right off a trail / walking area. (Don't want to make it too hard to get to). In my club we have hidden it in many other places though including hanging it in a tree, in a car, inside buildings (make sure you get permission!!), using a long cable to place the antenna 20 - 30 ft away from the fox burying the coax underground as it goes (this works well since you can just have the antenna sticking up which is much smaller than the ammo can and harder to find BUT may get stepped on). We also thought about burying the whole ammo can underground but our fox already had over-heating issues so we didn't. You could do this as long as your fox had very good cooling or is very low power. For future fox hunts we have considered putting the fox inside a backpack and have someone *NOT IN THE CLUB wear it and sit on a park bench. We have also thought about a moving fox but we decided against it due to being nearly impossible (at-least at our skill level).
Some other ideas I myself have thought of is placing the fox inside either the fireplace or the on one of the support beams on the covers (if your local park(s) have them). Also (if funds allow) buy / make a new fox that is small enough to fit inside a coke can or other small objects that you can usually find on the ground. (Warning: May get thrown away if park or area maintenance pass by.. hide in a good spot).
That is all I have.