That makes perfect sense, I did some testing and tried your method and mine. Mine can cause issues depending on certain scenarios. If I Split the sprite into two images, and make the bottom one solid, it works ok, but if you have larger sprites that are tall and you need to have them overlap when they are in front you get clipping or issues where the sprite is on top of the bottom of the object, but their head gets underneath the top portion of the object, which causes some real oddities. I think your method works great.
You should do a Tutorial on that as I think it would help a lot of folks especially those doing isometric view or event top down type of games.