I recently got an ABUS link lock , all hardened steel , it's advantage , the 6 links fold,
and goes in a storage pouch that you can strap on the frame ,
and the links don't let you get a pry bar on it like It's possible with a U lock .

add a length of hardened steel square link chain, and it should be there when you return..

proportionally lighter the bike, the heavier the lock to keep it.