Why does it have to be in the boots? it could be anywhere, as long as everyone wears it in the same place and then the unit becomes the arbiter of offside, and we can sack the shit about legs and arms influencing the decision process.
Absolutely. Put it on the front and back of every player, then set a defined limit on the distance between them to determine offside.
It's a simple scenario for me, you predetermine what distance is required for an attacker to 'gain advantage ' over a defender, and as long as this is agreed & remains constant, then the arguments go away.
For example, a toe beyond a defender is not an advantage, but if the attacker is shown as, say, 100mm 'goal side' of the defender, then he has gained an unfair advantage and is therefore offside.
I'm sure there will be the "yeah, but what about" posts in response to this, but nothing is infallible. However, as long as the parameters are agreed, it would remove objectivity and, as you should be able to get almost instantaneous measurements, you wouldn't get the delays we currently have.
Everyone accepts goal line tech without argument, this would follow a similar path because it removes human error.