I did find a library called Nez that among many other things do offer a simple solution to create and manage levels (scenes) in MonoGame. The library offer many useful features but in case someone prefer to do it on it own way, it certainly provide a nice example how something like a LevelManager could be implemented in practice 
I find it very useful even just to look at the source code.
Link:
https://github.com/prime31/Nez