90 acres of one hay crop is going to be hard on scheduling. While you want to cut on a 28 day cycle, lil' ol' Mother Nature might have different ideas. E.g., last spring, my orchard grass was prime about May 22nd, but the weather didn't cooperate until June 16th.
Since you are south of me, you'll get a lot more gulf moisture. And get it earlier! This means that you'll typically need around 4 (or more) days drying time, but you'll be lucky to get it.
I would suggest both.
Get the tedder first, then get the acid applicator. The tedder can be used on every cutting; acid only when caught in the weather bind.
Just my thoughts....
Ralph