by the way slippers are bad when its raining heavily
you walk 3 meters and the slippers have been eaten by the mud and you can't find them again
regarding the glass I never had a problem with getting Some Whiskey/Rum in glass bottles as long as you:
- when initially moving it in keep it inside backpack or something
- keep the bottles in Camp
- don't walk around with the bottles but only use them to fill the drinks
- if inspected and bottle is mentioned
react very calmly and say you use it responsibly only inside the tent to fill drinks or refill to plastic
Never had a problem all these years even had my backpack inspected twice when entering when I was at the NoCars campground the first years of the glasban and they let me in.
Inside the car its easier anyway as long as nothing is visible from the outside your car wont be checked they will basically only act against peoples who exaggerate like if you would come with open trailers full of visible glasbottles. That said I would still recommend minimizing your glas especially for beer take no glas as you can carry the cans around then but if you only have a few specialty brew stuff then its fine but there is no guarantee as the official stance is none allowed.