I’ve done some tests, So far it looks like the character class has to be edited to allow you to walk on any surface.
You can check out this for what you want.
It seams that the author( I assume it is the same one) is working on getting this added to the engine, But I don’t know if/when that will happen(probably in 4.13 at the earliest if it does happen).
I will continue my experiments with this.
HTH