Early in my career, I used what were called polypins in the UK, I believe cubitainers (for wine) over here. Similar construction material-wise, but with a simple spigot that stays positioned at the bottom. Back in the day, they were not only standard equipment for British homebrewers, but breweries sold beer in them for home/party use. With no way of venting other than opening the spigot, they always looked ready to blow. SOP was simple: draw a couple of pints every day to relieve pressure. Tragically, this means you must regularly drink beer.