I'll bet your screen isn't as much of an air brake as the rest of your bike and you.
Perhaps it's time to go for a fairing?
I've toiled with putting a tachometer and rev light on mine there's plenty of options out there I was looking at fully programmable car units encapsulated in a nice home made stainless case but then I thought just how accurate is it without a dyno etc
Either way it's still a lump hung out front. Maybe if you want to squeeze that little more you'd be better just shaving the weight or reshaping it for less resistance.
Just my tuppence for what it's worth
Just have fun however you go