All platforms above 4' require handrails and unblocked access stair. If blocked by piping/equipment, you will need to provide access stairs on each side. If blocked on 3 sides, you need to enlarge the platform to allow walk through, and perform maintenance tasks. If the owner insists to skip OSHA requirements, give up the job, as the owner likely to involve you later on unsafe designs somewhere else. The safety is for preserve human life, not for OSHA, nor the owner.