Resourcefulness and stupidity. If my options are out then my first course of action would be the church.
Repost:
I decided to cycle from Serbia to Croatia for an hour. All I took with me was the bike with rear bike light, passport 5,500 dinars ($55) and a phone with 40% battery life. The typically aggressive Serbian border guard let me through, but on the other side I was interrogated for 90 minutes by the placid Croatian boarder guards as my passport had a problem which meant it was invalid. They told me I had to go back to Serbia, but on trying to go back to Serbia, they also spotted the passport problem and would not let me go back. The Croats said I could stay in Croatia and one of the guards let me hotspot his phone to get on to AirBnB. My tourist SIM had expired a few hours earlier. There was actually a place in the village, but being Scrooge incarnate I decided to save $20 and book a place what I thought would be at most 90 minutes cycle away. Five hours later I arrive at my destination at about midnight, three hours of which were in the pouring rain and with three stops by the Croatian police. Having not eaten since breakfast I took some apples from the side of the road. It's also pretty difficult riding with car lights beaming in your face all night. Once I realised how far I had to travel, I tried to book into a hotel, but turns out dinars are not popular in Croatia.
On arriving at the AirBnB, I was confronted by an angry middle-aged Croatian matriarch, who switched to mothering mode when I told her why I was so late. However, I wasn't able to get to sleep that night and after a large breakfast I biked back all the way to the Serbian border, a round trip of 180km with no sleep in 30 hours, in the pouring rain. I had about 5% battery left on arrival at another AirBnB and luckily they were prepared to swap my dinars for kuna, which I used to go to Zagreb with, booked into another AirBnB and used my encrypted bank details which I had stored on my phone to take out 200 EUR worth of kuna from Western Union. I used this to get an EU-free emergency passport.
My plan B was making a raft from my bike and trying to make it across the Danube.
For extra precaution I think it's best to go with:
USD/EUR in cash
Multiple cards
Phone with encrypted banking details
Ideally same details on a waterproofed SD card embedded in your shoe