Let's look at why each item is so important. Locks and alarms keep harmful items out of reach and out of sight of the person who cannot control touching, tasting, stashing or stealing what is not theirs and what could be harmful to them, including unauthroized food, money, medical records, medications, and certain items of personal property, like keys and credit cards. If you have ever had your credit cards stolen, or couldn't drive home because you couldn't find your car keys, then you understand. Alarms just make it easier for you and relieves the anxiety the person with PWS might have without the added security. About the same as the deductible on your home owners insurance.
Awareness is the first step toward understanding, which leads to changed attitudes.
Strive for awareness of the disability by you, by the person with PWS, by all family members, neighbors, local police station, school, doctor, and every person who may have contact with the person. If they understand the syndrome, they will be better prepared to deal with any difficult situations that they might encounter, and maybe crises can be prevented before a situation gets out of control. They need us to monitor them because they are not able to monitor themselves. The poor judgment and poor impulse control is part of the disability, and it is beyond their control. This is a neurological issue, not a behavior problem that they can learn to control.