You can always climb stairs in a tall building. 100 stories up and down with the pack would be a real help, at least it would tell you whether the trip is ridiculous or doable for you. Do it about 5 times to simulate the canyon. <img src="/forums/images/graemlins/shocked.gif" alt="" /> Oh and you can break in boots that way too. I used to soak em in water over night, put em on really tight, and climb the stairs in my apartment building till they stretched.

Tarps. I know you're going in June, but it can snow any day of the year up on the rim. While it was Easter, I have camped in a blizzard at the rim after a nice hike up. You should be prepared to pitch that tarp in a howling storm if you are gonna depend on it for shelter. Tents are heavy but offer more protection - which may not be required. <img src="/forums/images/graemlins/smile.gif" alt="" />

Why in the world would your pack weigh that much without an 8 man tent? Maybe you shold post a gear list - we are really good at dissecting them.
<img src="/forums/images/graemlins/grin.gif" alt="" />
Jim <img src="/forums/images/graemlins/cool.gif" alt="" />
These are my own opinions based on wisdom earned through many wrong decisions. Your mileage may vary.