I am not sure how many brewers here brew cask ale. I small batch BIAB brew and have made it my mission for 2022 to nail a cask ale best bitter. I have my first Best Bitter in a 5 litre minikeg/cask, the party keg variety. Now when brewing real ale and casking it, venting is one of the steps. I can't get spiles as soon as I need them. I have a small cork that fits the hole in the rubber two piece cap. Think this will work in the place of a soft spile? Cork is porous right? See photo. Cheers