I guess if you have a nice photo of a girl on the screen, you could always lick it!
Being left-eyed, my nose always leaves terrible smudges on the rear screen of my 5D3 too.
At least with my 60D, I can pull the screen out to the side.
I also use lens wipes on my 5D3 screen, and they work well.
While I've got one in my hand, I also grab my smartphone and give it's screen a wipe over too, after I've cleaned my glasses.
A single wipe will clean a pair of glasses, your camera screen and a phone screen, and still have some life left in it.