Ok, thanks. So for now the best way to access the UserCustomField in the widget is to just whitelist the user_field_X name in site settings.
Otherwise, in the plugin.rb I would need to do something along the lines of, find UserField with name “myCustomField”, get the id and then whitelist user_field_<id> somehow without site settings. Obviously possible but maybe just easier to look up the user field number and do it in site settings.