Yep, it's always a good idea to pack an extension cable and/or splitter. This is also a good time to mention that if you are planning on having a group campsite, you should make sure to fill out the campsite sign-up form:
This will ensure that we can provide enough power for your campsite and facilitate any other needs you might have.
That being said, we also generally have power available in the Prime Dome where the main talks are taking place, and around the camp at the workshop locations like the Yoga Studio, the Lower Field stage, and another good go-to device charging spot is the Ada's Cafe in the Tree House. There's also a lounge below the Doe Bay Cafe that has power and is generally open to the public.
Thanks!
-David