Yeah it's def a pain to do! I did a lot of cut outs and custom mods to my old Z. My Dremel was like my best friend lol! The new Rex's are just horrible looking with all the fake vents IMO though...they ALL gotta go!
Gotta get yourself a Dremel man. Makes intricate work like this a breeze. I'd recommend one with speed adjustments as well. I got mine from Harbor Freight (not sure if they're by you) for $20 like 4 years ago and it still works great.