It's good to have a note from the park for your exchange for the front gate. That's where you will have to lay down some cash if your not bonafide(paperwork in your posession). The reality is, your permit is paid for with your trip if you are actually on the trip participant list(which It sounds like you are), but the front gate has little access and a long line behind you. If you try and run the "hey I paid and I can't believe this is happening at this point" Run at the front gate they will probably have the compassionate eyes, but the unforgiving lips. With someone behind you honking. This is an area they are currently working on. If you called 1 800 959 9164 before noon tomorrow and asked them to fax you your official paperworks before you leave, they would probably gladly do it for you. After you pass the front gate, the trail Rangers are watching out for trouble(dehydration, terrorists, etc.), not river trips. And everyone can hike daily anyway without molestation so unless you are doing something majorly illegal, wheels, trail cuts, etc. you would be lucky to even notice one. It might be even borderline illegal to mess with you, but they aren't looking to make their job tougher for some high functioning fun junky anyway.
If you haven't left already, call them at 1800 959 9164 and get them to fax you a pass through the NY Tollbooth.
Grab a map and park at the top of the trail. Your hikers will appreciate it. Go into the hotel parking drive between the small 10X 12 cabins and park with all the other cars. Trail is right below you.
2 1/2 hours-4 hours down. Early hike at Sunrise is a Navajo Tradition. Prayers to the East. Ken is right on!
After writing all of this and rereading your post correctly, if you show your pass at the gate your done for all practical purposes. The strip search is over, you can pick up the soap
Your bonafide. VIP.
Have a great trip!