I used something similar for a while, just slightly larger, and that did the job well:

https://www.deuter.com/AU/ae/hiking/...0218-blue.html

The downside of using a backpack is the sweaty back problem. If you don't have to carry anything particularly large and solid (eg a laptop), a bikepacking seat bag may be a good option, and I recently started doing this for commuting with a Topeak Backloader:

https://www.topeak.com/global/en/pro...969-backloader

With the 10l version it fits food, clothes, and shoes with loads of room to spare, and tightens up easily so the spare capacity isn't hanging loosely at the back.