I vent my plastic cans with a schrader valve like you you use for air etc. Drill the hole a little smaller and screw it into the can with a little silicon. Remove the valve core and put the cap on it. No leaks. Remove the cap when you need to vent. My main problem is misplacing the cap so I keep extras on hand.
This made me recall using a potato for a stopper on kerosene or coal oil cans when I was a kid. Seems the metal screw-on cap got lost soon after purchasing a can.I fitted schrader valves to a couple of 5 gal fuel jugs. Both broke off in less than a month. The rubber "groove" broke at the base. I did not expect that, I guess I'm hard on them.
So I wittled a couple of wooden plugs, and tye the pegs to the jug handle with string so they don't get lost.
With temperature change, I have had the wooden plugs loosen, but it's easy enough to check them before handling the jug.