This may not help much, but we were in a similar situation.
Not sure if my son will even get accepted, but in his portfolio I used a picture of a creative and fairly detailed project he did on a poster board, a speech he wrote for his class president campaign, and several videos of him talking about the Lord of the Rings books we/he's reading, plus a video of him talking about deep sea ocean life.
It was not pages and pages of portfolio items, but sometimes being concise is the way to go (I hope).
By the way, my son is the same age.
