Coordinating logistics across borders.
Check each country's specific requirements before you go, since driving-side conventions, road signage, and documentation expectations can all shift at a border crossing. Confirm with your rental company whether cross-border driving is even permitted under your agreement, since some restrict it entirely.
Build extra time into your schedule for border crossings, which can take anywhere from a few minutes to over an hour depending on the crossing and time of day. Keep your passport, license, and IDP together and easily accessible for each crossing.