Alexandroupoli is a city in Greece close to turkish border.
East towards Turkey
You can try to hitchhike north of Alexandroupoli at the entrance of E90 but not many greek people do cross the border. You will have to count on the few romanians and turkish who stayed in the city and head to Turkey (mostly in the morning and beginning of the afternoon).
The easy option is to take the bus from the KTL station in the city center that drop you right at the border (last stop). It costs between 2-3 €. From there you will not be able to cross the border by foot, but you should easily find a car/truck that will take to Keşan or even further.
You can walk along the main road 2 to the east for 20-30 min. At the end of the city, just before a bridge, you will see a dirt road on your right that goes under the railroad. Follow it, you may encounter some dogs barking, but they should not come closer. You can start looking for a nice place to put your tent out. If you cross the the dirt mound on the left, you will be invisible from the dirt road.