you cant really bot bandits, you will die fairly quick. just do soul wars bot, 100+ setting will get you around 5 zeals/h. Thats like 35k exp an hour and 10k exp from the prynefiends so its 45k exp an hour
High range def plus food would make it possible, I wouldn't do it there though, you'll get cannoner's on slayer tasks taking most of them or just reporting you.
I'd do experiment or you could try souls bane rift training area. If you dont mind slower xp but less chance of being reported you could try the souls bane rift training area, the angry beasts give like 200xp, u'll need fairly heavy melee def.