Im getting a loaded vanguard, what flex should i get?

I weigh about 110 pounds and i would like a flex that would be bouncy like the ones on the loaded videos, and possibly be able to do tricks like those. I would like a 42" but they only come in flex 1 and 2, then the flex 3, 4, and 5 come in 38". What would you guys recommend? I currently have a Arbor blunt koa board.