Super simple mod, it's just keep your spot icon up for 12 seconds.
But why 12 seconds? it's the maximum duration of a spot (10+2 with 2 seconds caused by the perk).
So if the spot icon disappear you are sure that you are not longer spotted.
Beware! If some spotter sees you whole time during 12s, spot icon will go out but you stay spotted! Spot icon will not lit up again because spot was not interrupted!