We are coming Friday for the Avett Bros concert and have paid for Terrace Camping. We have one person in our party coming Saturday. Is this going to be a problem for them to get in?

No just meet them at the entrance of terrace also contact live nation

How much is the Terrance camping?

As an employee of the gorge I can assure you that as long as you explain the situation to the person checking passes when you get there you will be just fine. People do it all the time.

Absolutely, everybody has to arrive together!!! Unless he wants to pay for another camping spot.

I don't see an issue, but to be sure contact them on the Facebook page directly if you have that platform. Or email directly as well. Shouldn't be a problem though.