Yes you can. I did this all the time at the office because we needed more screens for the tasks we would do. Just remember though, that when using an APU to push a display, some of your CPU performance will be going to that display also. Your APU temp will also go up a bit, unless your fan is cooling it enough, and RAM is used to push APU power, so you may take a bit of a hit in performance on your primary display connected to your GPU.
In my work, it was fine because we were dealing with primarily still images. But for your tasks, you would have to try it and see how it works for you.