render to texture

Render to texture is a very handy functionality. Imagine your game allows for some character customization. You have the body, some different hats, different clothes and other small stuff. Now the easiest way to render this is to just draw it piece by piece every frame. With the proper Z coordinates everything falls in place. But you now have like 4-5 draw calls for one single object. Worse, you might have different textures and swamping textures is expensive....