What would you suggest?
A lot of controls and distance on these maps so a lot of work/risk to put out conventional controls, I think taking photos on phones etc would prob be slower than writing. Maybe QR codes?
Or possibly just upload your GPS trace to show you've been there?
Agree conventional controls aren't going to work. QR are as slow as pen. Unfortunately GPS isn't accurate enough - at least not until Galileo is operating https://en.wikipedia.org/wiki/Galileo_(satellite_n...
I think something like NFC tags or iBeacons/Bluetooth could work well. They are really small and cheap, non orienteers wouldn't even see them.