Hello Commanders,
All landing zones are generated at the start of a world for the max amount of player slots specified for that world. There are no new player spots added after that. Nevertheless, forgotten camps and OPs may spawn among those landing zones as they would anywhere else.
That does not inflict with the blocking radius for base founding. IF you want to expand your territory move forward, not backwards. As stated above, Reservation Markers are a visual aid, one that have no effect on spawns of players or Forgotten or otherwise. They can also only be seen from your alliance peers anyway.