Your cathole shouldn't leave a trace - that is, shouldn't be visible to anyone after use. So in that regard, maybe work on making your covered catholes invisible. 

When I use them, and when I've read about them, they're always small and only big enough for one use.

Properly made, closed catholes shouldn't attract animals. Open ones might, but I've never left a used one open. One thing I've done that was helpful was to dig one before gong to bed so that I can use it first thing in the morning without need time to locate and dig one.  

Also, a cathole shouldn't damage the environment. So, save the top layer, whether grass or sticks and leaves, and put it back. Your droppings and toilet paper are fertilizer, and will become part of the earth quickly, benefitting the environment.