Might sound daft, but would you be more comfortable if you "sat up" a bit? I find that with the stock screen, the wind blast is coming onto my chest, relieving the weight on my wrists. So, conversely to you, I've always fought shy of "double-bubble" and similar screens, concerned that they might merely deflect the wind-blast onto my helmet.
I've clocked up plenty of motorway miles, including a trip to Scotland last summer, at speeds "as fast as feasible"

, and I can't say I''ve found it uncomfortable. Of course, how tall you are, and what helmet you have, are factors too.
If you're the type of rider who likes to "tuck in" behind the screen, then yes, I guess a bigger screen could help you. They're not that dear, anyway (leastways, not compared to most of the "bling" enthused about around these parts!

).