Give the wording of Decision 33-8/17, I don't believe such a local rule would be authorised. Safety nets are not unusual on a golf course. Only if it was temporary would the standard local rule be appropriate.
33-8//17 Local Rule Providing Line-of-Sight Relief from Irrigation-Control Boxes
Q.Irrigation-control boxes, which are about two feet wide and four feet high, have been installed near a number of fairways. Would it be appropriate for a Committee to adopt a Local Rule under which relief would be provided from such boxes when they intervene on the line of play, i.e., line-of-sight relief?
A.No. Providing line-of-sight relief from permanent immovable obstructions is not authorized, except in very unusual circumstances. It is not unusual for irrigation-control boxes to be located near fairways.