Before setting up iwisp I was thinking of setting up oxidized ( https://github.com/ytti/oxidized ) to facilitate automated backups of the configs of all tower ubnt devices for easy setup/redeploy after device failure.
However, it occurs to me this functionality is probably very easy to implement in iwisp since config backups can already be done with a single button press in the management interface (works great!). Having the default to be weekly or monthly backup tasks and saving perhaps the 1 prior backup configuration for any device assigned to a tower might be cool.