In 50nl FR I think its safe to assume that most opponents arent 3betting light, most oops have a 3bet % of 2-3% which is your standard range.

Sure you can 3bet selective opponents light IP, I have no issues with that. However I really don't think you should be 4betting light vs most players without some kind of history or their 3bet % is way high.

I really don't think you need to be getting uber aggro preflop to beat 50nl for a decent win rate. Sure it's nice to know the theory but there's no point going 2 levels above your opponents understanding of the game. You'll just pwn yourself.