Option 2 is limiting spies ability to open gate which means - That they will be unable to open gates at all
And yeah for Option 3 if someone abuses the rules in regards to spying there will be no option to redo the turn, rather if you find out after 10 players have played their turn for example then that person who abused the rules will be put into suspension and his next 5 turns he will not be allowd to use spies to open settlement cities.
Anyways, you realize that Option 2 is pretty much saying that No spy can Open any gate whenever (also will be monitored).
Ill add you for option 2 unless you want it changed,
Finally, I did look into changing the % of spies rate of success for opening gates,
But it only works on a individual basis, and everyone would need to upload the same file inorder to take ahold of the limitations, and if they decide not to, accidentally or maliciously they would have an unfair advantage... catch my drift?