How about adding a Sun Visor at the roof back corner?

Reg cab, base model.
I know this may sound lame to some folks, but that bright sun that sneaks in where the visor doesn't block it at the side window, is annoying! I am talking about the gap at the end of the stock visor, when it is positioned at the side window. There is at least 8" of unblocked window top, and if stuck that way awhile, it gets really old!
I can up with the idea of adding a 2nd visor, mounted up in the rear corner of the cab roof, just like the stock visor is mounted at the front corner. Both visors could then be positioned at the side window to block the entire length at the top.
The big question is: Is the airbag in harms way if I drill holes at the top back corner?

 

http://www.youtube.com/watch?v=HByR6YM71p0

 

I never use my visors, and it's very sunny here. I just raise my head and tilt back...