It may be adventageous to have all three people in trailer ops verify that they are ready before the starter sends the next car. This may only take a couple of seconds, but it sounds like it could save a tremendous amount of time.
I posted the following registration related info in another thread:
I worked SCCA registration last year, and I can point to several things that cause a slowdown.
1. People that do not know what class they are running
2. People that stand in the wrong line in registration
3. One list of car numbers that is being maintained by someone that is
also registering entrants
4. Multiple drivers driving the same car that are not sure of what number
they want to run
5. Lost registration cards
6. "What numbers are available?"
7. "I'm paying for my buddy too, but he is in the other line."
8. "My buddy paid for me, but he was in the other line."
There are some other things as well, but these are the ones that stick out in my mind the most.