Rule one: soft bag, not a suitcase. A 4WD packed for fourteen days has no respect for hard-shell luggage, and neither does the corrugation on the Telegraph Track.
Rule two: quick-dry everything. You will swim most days — the Wenlock, Fruit Bat Falls, Eliot Falls — and cotton stays wet long enough to be miserable.
Bring reef shoes. The best swimming holes have rocky entries, and the guests who pack reef shoes are the ones still smiling on day nine.
A head torch, a wide-brim hat, and a decent camera — or just a phone with storage cleared. You will take more photos at Pajinka than you think.
And leave room. Not in the bag — in the plan. The best moments on a Cape York trip are the unscheduled ones. That's the whole idea.