Plundering does not involve clicking on your physical character, but via the list through the Intelligence Captain in group base.
What happens is your SS mission along with all the other numerous S missions and below will appear as a scroll down list. SS mission will appear at the top. Its a 1st come 1st serve type screen, so all the plunderers see the same list. So if someone clicks it first, they get it, and it disappears off the other plunderers' list. So its a hunger games for all the SS missions and if you convoy at such a time where all the plunderers are like hyenas, you'll definitely almost immediately get plundered. And once that plunderer clicks on the SS mission, his/her character will teleport to where your Convoy is, so it appears like he's/she's physically there, and will remain standing there after the battle.
So although it appears that the plunderer is actually clicking on you by camping nearby or close to you, he's/she's not. So in fact, you can run around the village with that Golden plunder icon above your head and not get plundered if you haven't clicked to 'Set Off' at your convoy screen.
I recommend doing all your S missions first, no one plunders that. Then leave that SS mission convoy towards the end of the day, when the event is about to end, such as between 8.30pm to 9pm (server time), as much plunderers would have done their plunders for that day. Or sneak those SS mission in during other event times like when there's Nine Tails, maybe about 5 mins before the Nine Tails actual attack starts, most top players are waiting in that screen, so they won't be plundering. Or when there's GNW going on, and you happen to be out early from your own group's battle.