We also bought such corner-installed tileable stainless steel shelves on eBay and had them installed by the tiler.
In the downstairs WC, there are two stacked in one corner, and in the main bathroom also two stacked, but in two corners. With 1m x 1m, you don't knock anything down there either.
About 3-4 bottles fit on the lower large shelf. On the smaller one, 2-3 bottles or other bits and pieces like razors, etc...
