burner seems safest and fastest

Or you could backup all you data somewhere accessible over a secure connection, wipe your phone before go anywhere, and restore the data once out of the country. You would need to do the same before coming back. Backup, wipe, travel, restore.

Consumes a lot of time (and data) which probably isn't worth it for short trips where your mobile data is costing you. But if you'll be gone a while and will have access to an unmetered network connection, it's feasible.

It accomplishes the same thing as wiping your phone at customs, but planned and executed in-advance instead of panic-wiping it in front of them. 🤷