Brisket Challenge: Brisket, charcoal grill, 2 hours-what to do

Can you cook it ahead?

Cut the brisket into smaller manageable pieces and use a push tenderizer on each piece a couple of times.
Marinate for the rest of the prep time.
Cook indirect for 1 hour and 40 minutes
Cook 5 minutes direct for color.
Let it rest for the remaining 15 minutes.
Obviously the pieces should be small enough to cook through in 1 hour and 40 minutes.
If you have a few bucks to spend and want to win, invest in a vacuum tumbler if the rules allow it.

"Vacuum Tumbling removes the air from a rotating drum and "tumbles" the product inside the drum. This "tumbling" under a vacuum allows the meat pores to open up and accept the marinade & water. The tumbling action of a few minutes allows for a greater pickup up of water and spice - 10% - 20% compared to 1% - 2% when soaking for 48 hours."

Here is link to a push tenderizer and a vacuum tumbler.
I have no connection to either company, just using them as examples of the product.
Although I have used a push tenderizer with good success.

Push tenderizer:
http://www.alliedkenco.com/catalog/product_info.php/products_id/2976

Vacuum tumbler:
http://www.marinator.com/lt10.htm

Good luck

how many portions do you have to turn in?

You will probably have to use something like a Jaccard to get the thing tender. You might also try using some tender quick to get a smoke ring.