It is impossible to mitigate all risk unless air shows are banned.
Folks,
Sadly, that is the effective results in Australia, it is well nigh impossible to stage any airshow over what is called (without clear definition) a "populous area" in Australia, leaving a very limited number of venues where a serious airshow can be mounted within reasonable proximity to a population that makes an airshow a viable financial proposition.
As soon as any (but especially aviation) government authority starts talking about "absolute safety" you know your proposal is in trouble.