Building on top of Trapdoors in Vanilla?

Trapdoors can be placed flush with normal blocks, either at the bottom, or the top of the block, like so:

This makes it an "applicable" surface to place items on. This video shows how to make Iron Trapdoor Shelves, and shows that items can be placed on trapdoors at the appropriate height.

The only issue is that Wooden Trapdoors can be opened/closed with a right-click, whereas the Iron Trapdoors need a redstone signal, so placing items on an Iron Trapdoor is just a straightforward right-click. However, you can place items on Wooden Trapdoors, by holding L-Shift when you place the item.