I can understand your unease. We ventured slightly further afield for the first time over QB weekend. I did as much research as I could on what recharging options were available at various locations and didn’t leave myself with a ‘single point of failure’ situation (one charger and it’s broken). However, you also need to be prepared in your scheduling for the charger to be busy when you get there.
I think you are wise to work on 180Wh/km. Just don’t let your holiday be ruined by anxiety.