Not possible to do both jobs at once? Sure it is.
As I said, this is the system under which I have operated for over 25 years, and it is flawless. This is a club with about 1,000 members, all of them are expected to know the rules and obey them. Failure to do so is grounds for immediate termination of membership.
At the same time, everyone is responsible for safety, anyone can call a cease fire at any time for safety reasons. The RSO is responsible for calling periodic cease fires for re-setting targets, etc. And checks that the line is safe prior to calling the range cold. Once everyone is back he calls the range hot. It isn't that difficult.