I actually built this last week. I don't know if this could work for multiplayer but it does work pretty solid for me so far. furthest I've gone is 300x300 and it worked fine.
(this is all assuming your map is a square)
take the world and break it into 9 different tilemaps. (we'll call them worldtiles) Each one being 1/3 of your map in the x and y direction
Make a node called "leapfrogger" and make a tic tac toe board out of 4 collisionshapes inside of it. We're going to arrange those 4 collisionshapes so that the 2 horizontal collision shapes are 1/6 the map from the top, and the other 1/6 the map from the bottom. The two vertical will be 1/6 from the left and 1/6 from the right.
When you hit the east collider, you move the three western world tiles 2/3 map width to the east, you will also move your leapfrogger 1/3 map to the east. same with the west, north, and south.
It's actually super easy to match up the tilemaps between eachother if you fill the worldtile 1 extra tile in every direction, update the bitmap, then delete the outer ring without updating.