Traveling the country and speaking to both Tech's and their Mgr.s I'm fascinated by the philosophical differences I find on this topic. From the Technician's viewpoint I don't see many "excited" by being on call as you state utility workers are. I've also found that the bonus or incentive is the exception rather than the rule. Kudo's to you for investigating this as a possibility.
The majority of frustration I hear from the on call person is the need to not cut our own throat. Meaning, as others have stated, that preventive maintenance is not given a priority. Or the need to keep OT low by taking the time spent in the evenings off the next day or two, thereby cutting the scheduled wrench time short for unscheduled tasks.
Management is frustrated at technicians that blame on call for every situation, or when a "band-aid" is placed on a problem and then not followed up on the next day.
IMO the solution to this is just what you are doing. Have a clear policy that the Leasing staff can review at move in so the resident is aware of what an emergency is and what it is not. Be sure that the policy is followed at all levels, not to use as the customer service nightmare response response of "that is not our policy so I'll be there tomorrow... Click..."
This policy is restated in the job description so that all new employees can set an expectation as to "family time" commitments to recognize that it is goes along with the job. It may be helpful to ensure a way to investigate an excessive amount of overtime on a community as being caused by a lack of personnel, time, accountability or training.
Many technicians are looking for their viewpoint and input (time and opinions) to be honored. Having a policy that allows for that "boots on the ground input" seems to be to be the path to success.