you don't need any levels for the tanning bot, high agility is good since you'll be getting more runs/hour, but it's simply running back and forth tanning hides
Don't forget you need a lot of start up cash if you plan to run the tanner for long periods of time. You can do 1500-1800 (or so i hear) hides per hr. Doing greens, this will be around 4m start up cash for every hour you plan to run it consecutively
I hear herb prices are already rebounding from bonus xp weekend, which would make profits go up.
However, the elementals guarding the gardens keep glitching into horrible spots now, and do not move for ages because of them catching bots 24/7, which make profits go down.
If Jagex were to fix the elementals movements so they do not go off track, profits would go up. But I strongly doubt they will fix that.
If you have found a way to stop people from luring the elementals and have found worlds where the elementals dont glitch multiple times a day, PM me and I will give you a weeks worth of my profits