If I’m being honest I am of the same opinion as Sir Stirling Moss, track limits infringements could be prevented by building the tracks so that it is not physically possible to exceed them. Some tracks do it very successfully (AND it adds to thrill of watching), Montreal, Monaco, Surfer’s Paradise, Birmingham Superprix for example (where the penalty for exceeding the limits is retirement, but the fastest way around the track is to push as close as possible )
This is why I think that infringements could be easily detected with existing vehicle hardware and track infrastructure. It is even something that could be used to inform viewers/spectators via the F1 App/online. Rather than using the race stewards to determine whether someone has actually exceeded the limits, they would be better placed to review whether there were mitigating circumstances (spin, forced off, etc); after all, there are only three stewards, but 20 cars and many corners per lap - do the maths and determine whether it is really plausible for all cars to be monitored....
Automatic monitoring is the only real plausible method.
Penalties for infringements could range from DRS ‘ban’ for one lap, then ERS ‘ban’ for one lap, followed by pit-lane drive-through penalty for a third infringement. All risk, no reward.