Seagulls? Surely there is something better than that.
I keep my botting for publicly visible activities to 4-6 hours at a time maximum.
Seagulls are the best defence pure XP per hour since they are the ftp mob with lowest defense. The more afk option is monks, but it's a lot slower.
@Second I'd personally recommend just autoclicking at monks for 6 hour intervals tbh. That's what I did, just have the mouse over an item in your invy or something that you can click infinitely without it effecting your position and make it click every 35-55 seconds.
I believe it to be inherently safer than doing seagulls that long since A. no one expects people afk at monks to respond and B. your play pattern will be identical to everyone else at monks (clicking in one spot every ~1 minute.
Of course you should half babysit the bot while you're low level in case they hit you too high and you die, but around mithril/addy it becomes almost impossible.
Source: I autoclicked monks 6-12 hours a day to about 65 defence (and then botted skilling on the account and got banned, which was dumb of me).