wrangler jk coolant/antifreeze overflow tank modification for upper vent hole

[14JKALTITUDE]

so to get rid of that smell that vents out, the upper vent hole, what size rubber hose would i need to insert into that hole so i can have it vent to the bottom? you cannot place a hose over the vent hole because of the way it is angle cut to the body of the tank? thanks.