I've got 7,460 rolls and 2,237 Passline decisions for 3.33 rolls per PL decision. If I wanted to roll 333 times for 100 PL decisions, hopefully buying-in with 20 units for PL-only betting will have a 3% Risk of Ruin.

Long term play? I'm not thinking so...short term wins; most players blow-up by putting winnings back on the felt. Discipline, that's name of the game. Your math is all wrong like most hear. Don't even think the math of the game is going to give you a profit in your strategy. Instead, prefect the math in your strategy to produce profits from the outcome of the dice.