I think that’s a really interesting ethical question, personally I think the profit incentive will cause a cobra effect type situation and these species will never be made extinct where they were introduced.

Having that in mind it’s a situation where one needs a crystal ball to determine whats the right things. A single large ecological shift, with all ethical harms that come with it, or a long term lower level of ethical harm.

I'm familiar with the areas in question and I fall on the side of believing that feral donkeys, camels, bulls, dogs, cats, cane toads, et al will never be erradicated as the area is vast and the animals are dug in; the best that can be achieved is to routinely cull back.

On another ethical point; the "natural" boom | bust cycle of kangaroos in the Australian outback - their numbers explode when there are years of rain, and the ground is littered with bones in the years that follow.

Is it ethical to cull booming kangaroo numbers (that will die in any case) to prevent the otherwise inevitable pressure on limited water supplies that follows?

This is the land of Peter Singer (and others).