Camping gear company Klymit has a nifty take on portable outdoor lighting: Inflatable fixtures. Their Everglow Light Tube folds down to practically nothing, and in its storage sack, can serve as a lantern…
…but you can inflate it to the size of a proper lighting fixture:
It comes in three sizes: Regular (18" x 3"), Large (26" x 3") and Extra Large (34" x 4.7").
The larger two sizes come with magnetic attachment points and even a dimmer switch. For any of the three, however, you'll have to bring a separate USB power source.