having a “second” render node is quite helpfull in this case. i’m using this trick myself and it works quite good.every 64 unit’s i create a new “second” render node near the player’s position , reparent all stuff to this node with wrtReparentTo.
this sorta requires you to sorta find a way to store positions of your models relative to the theoretical center of the world.
well if you divide your space into huge cubes with. lets say each one 1000 units side-length and you number them through. then you can easily say keep track of things.
it sorta allows you to have virtually unlimited world-sizes 
i think dungeon sidge used the same or at least a simmilar trick.