planting masdevallias

[escualida]

I only have the one masdie so I don't have much experience. I think I'm going to use the idea of putting sphag on top of the LECA but I'm worried, how do you know how high up you can put it? Is there not any concern with rotting the bottoms of the growths? The sphag in this case is probably going to be consistently wet and won't dry out, so I'm a little worried and want to make sure that it's potted correctly.