We are using Photons in our products which are all used indoors. We use softAP in a similar manner but rely on use of a mobile device browser rather than a mobile app. We also have a screen and buttons on all products so a user can see instructions and gets feedback on the device about the progress of setup (there is a timeout) and also whether the setup is successful or not. We have also found that the setup process using softAP is very sensitive to having enough available memory and so this is checked before the WiFi setup is started. If there is insufficient memory the user is asked to restart the device which always will recover the memory.
This works fine for most users but recently we have large universities and some schools who have WPA Enterprise and the extra data entry and memory requirements have meant that we have had to look at other methods to enter data - either on a memory card or via a spinner control on screen (which is tedious). Typically though the product will only have the WiFi details entered once and items do not get moved around.
I think you main problem is with having a headless device with only a single led and a few buttons as a user interface. Another idea might be to try BLE with a GEN3 device (Argon) and do the setup via bluetooth or even BLE from your sensor in the hive to a gateway device. I have been asking for the BLE setup APP template from Particle