Actually you wouldn't get banned if you do solo's by botting, since no one could report you. Other than that I support and good luck to your 120 dung journey.
I'm suggesting to keep the 10 seconds timer, I've been doing DM's lately and they always run. People dislike the drops, so it's best to remove BH and PVP worlds from RS.
Getting 43 Prayer is very useful, as you said PJer's often like to jump on you with a 2h while you're low on hp after a fight. So set the "Protect from Melee" prayer in the Quick Prayer list if you're planning to get 43 Prayer.