I was writing on a map a while back, and wanted to create something similar to the "too many turns" effect from The Stanley Parable: HD Remix (Walk to a corridor, turn left 3 times and come out on the other side). I had 2 thoughts on how to accomplish this, and neither of them would look seamless with multiplayer.
/tp the player to a relative position.
This was my first thought, and the problem is, obviously, that if someone was watching the teleported player, they would see them disappear.
/clone some blocks over the player's area (or use structure blocks)
This would have the problem of causing the world to noticeably change for other players. Worst yet, it could actually pace a wall over someone!
These are the only two solutions I could think of that look seamless in single player; I couldn't think of any that might work seamlessly in multiplayer. Any help would be appreciated.