I run a few trucks with 03-04 style marine covers like this that originate from Bean.
That breather you mounted will make a mess real quick over that clean engine bay. Also the smell of blow by and fresh zinc and Rotella will be strong in the cab from pulling fumes in thru your fresh air duct.
Cleanest way is to use a catch can and retuning oil to the sump. Have a secondary hose for vapor fumes plumbed down beside motor near the front driveshaft but not directly over it. My Hellman use's this setup it's clean and works great.
There is a black baffle inside toward the rear of the valve cover. You can weld a large A&N fitting to plumb your hose off of also if you don't want a catch can but does dribble oil on motors that are pushed hard.