I used a back pack for about 14 years. I prefer my Carradice saddle bag that I've used for the last three years. No rack is nessessary. I can put my work clothes, lunch, tool/repair kit in my Barley model. Thinking about a little more space and getting a Long Flap Nelson.
https://www.sjscycles.co.uk/luggage/...raps-18-litre/