Is it fun to ride there and back and will i need panniers and can i get away with a large kriega rucksack or will i need some panniers on my 999?
It’s a long way to ride for a short 3 days but why not make an extended trip. What you will need is a change of PPE gear for riding in (not mention a change of off bike clothing). It will undoubtedly be about 16 degrees and damp in the UK and Northern Europe, then it will be about 0-3 degrees as you cross the alps followed by 35-40 degrees when you get to the Adriatic cost.