Much as I love technology, there's no way you can trust smart phones to provide information to and from the back to the front of the ride- it just adds another complication. Plus of course what happens if there's a power cut in an area when we're passing through? Although obviously that then means no mobile phones anyway. If you really wanted to have multiple system redundancy, then someone at the front, middle and back should have walkie talkies.
For the bigger rides, (expanding on an idea raised by Adrian in February) to help ease the issue of some wayfinders hanging around at junctions for a long time, one option would be to put people in groups of 3 or so, with a fast person near the front, someone expected to normally be somewhere near the middle and the last person in the last third of the peloton.
The first person is then used as a waymarker, and then they're replaced by the person in the middle as they go past, letting the first person go zooming back towards the front, and then later on, the middle person is in turn replaced by the 3rd person in the group. If you have a number of these groups, they each replace their respective partner.
The phone numbers of the main leaders & TECs, not just Simon, needs to known to each other, and possibly it would be useful for someone else to also have a copy of the master list of participants with their numbers.
At the start of the ride, especially on ones where there are a lot of first timers, the pre-ride talk needs to make it clearer exactly who the TECs and leaders are. Should they have somthing distinctive like a sash? On March's ride I spoke to someone who wasn't sure who they should be looking for.
On the rides I do, I have printed copies of maps covering the route. And following one incident, I now ensure they cover a wider area than just the expected track, to allow for unforeseen things. So again, it would be a case of ensuring that a number of people have maps (or map enabled GPS) in case they need to work out where people have gone, or to help people get back on course if a group has gone the wrong way.
However, as stated above, you can't predict and take care of everything that might happen, so it's important not to lose sight of the overall intention of the FNRttC -
night rides are cycling with conversation; with a touch of the exotic and a smidge of romance.