Level streaming and Loading/saving game

Hello,

we are currently creating a game with multiple (more or less) closed rooms. Since the player is only in one room and need to get a key to open a door to the next room we tought about streaming levels to improve performance. So the thing is we built every room in a seperate level. To create seamless walls we created the first room with the wall to the next room. The second room does not contain this wall (so its not doubled) but contains the wall to the third room and so forth. So now if the player is in the first room, the second should be loaded at a certain point. If the player now enters the second room, the door behind him is shut so the previous room can be unloaded and the 3rd room can be loaded etc.
Now our problem is, how to create such a behaviour. Also, how to create level loading / saving with this in mind?
I had a look into the level streaming system but as I think it needs a persistent level in which all sublevels are added in the “levels” window. But then how to load the game into, say, 3rd room, without loading all other levels too?
Also, how does lightmaps behave here? Is this even good practise or should we just create all rooms in one big level and hope for view culling?

I hope you understand my problem.

…exact same problem in my side… did you find any solutions thou ?