I don't know what laws might apply but since I used to maintain the certification databases for the American Petroleum Institute I would strongly discourage any workarounds. In the USA every nut, bolt and screw used in the oil industry pipeline is certified by the API. If you wanted to connect any device to the system you'd have to get it approved, tested and certified.
I would guess that the lack of a unique IP is just the first layer of security. If you hook two devices to the pump a the same time it would probably trigger a shutdown of the station. A subsequent internal investigation would find that someone had connected an unauthorized network device to the system. I won't guess what would happen after that but I wouldn't be surprised if it set of alarms in one or more federal agencies.