I make $30/hr + bonuses at 100NL right now...so it's not that hard
So, I agree with ex on basically everything he said.
You really want 30x to play will confidence, and 40x to be fully comfortable. 20x is really the minimum to play full time at any level.
Take out the absolute minimum from your roll if at ALL possible. You win more/hr when you can move up and be stable there...so you want your roll to grow as fast as possible. However, you sound like discipline is the #1 priority and you need to be extra careful to stay within these bankroll guidelines.