Monuments High Radiation for Not-Auth Players

[Frommy]

Hello all,
I'm working on a big project with some other friends, a new way of playing Rust by adding side quests/ a story (missions).

Players are supposed to follow a path and so, to finish (for example) the monument n °1 before being able to join monument n°2 (same for n°3, n°4, ...).
To prevent a player from joining the monument n°2 I was thinking to set high radiation values only for the player not authorized yet. Other players that previously completed the monument n°1 will be able to join n°2 without any radiation problem (or with basic radiation values).

How does the server know if a player completed a previous monument and so letting the player to join the next one?
An idea was, for the player, to press a button at the end of a monument and in that case the server will add to the next monument whitelist the steam ID.
Since I don't know the possibilities that the Rust coding world offers, suggestions and variations are welcome.

Someone suggested me zone-manager plugin but, in my opinion, having players teleported back because of an invisible wall sounds annoying.

Another cool idea was to add immortal AIs before a monument checking if a player can joins the monument. If not, the AI will warn to stay away or else they will open fire. But this sounds way more complicated.

More info - Discord: Thomas Marcon#2889