Perhaps I'm underthinking it, but... If the RO is going to carry the gun, the carry method should be of sufficient ability to retain the gun through common physical tasks associated with the job. If it's not, the RO and gear are excluded until such time as it is. In the event of mishap, sanction proportionately for the level of oversight or incompetence demonstrated.
With the above, let the RO carry as they see fit.