Easy 10
Brain dead MUG SHEEP
I've just thought of this, not sure if it has been mentioned elsewhere. All players shirts to be fitted with the same technology as the goal line tech and fitted on their sternum area. The goal line /offside technology could easily see if there are 2 players ahead. It may still come down to millimeters but we won't see it and it will be an automatic alert to the ref if offside. They could be like a 10mm disc and if any part of that disk is overlapping a defenders or offside, it's off, if clear and behind the defender it's on. Obviously this can only be done in professional leagues due to cost etc. I think I've found a winner.
I'd take this a bit further, and have the equipment (sports bra ?) that the player is wearing illicit a mild electric shock whenever they stray offside, similar to being poked with a cattle prod. The shock level would gradually increase in power according to the number of times the player is caught offside, until it ultimately becomes like being tasered. At which point they should probably be subbed.
They'd end up timing their runs better, so everyone's a winner.