From Croatia to Syria through Serbia/Bulgaria/Romania/Macedonia/Turkey

Hello! In about 10 days(around 10.june.) I'm starting a tour from Zagreb(Croatia) to Istanbul. My plan is to follow Danube from Belgrade to Bucuresti and to Danube delta in Black Sea, then follow the Black sea coastline through Constanta, Varna and Istanbul. Then, if I have time and if manage to get a visa I plan to go to Ankara and from there to Aleppo(Syria) by train. If Syria doesn't work, my plan is to go from Istanbul to Skopje(Macedonia) and follow the coastline back to Croatia.
It is my first big ride and I would appreciate any information about wild camping and friendliness of locals and any other useful info on countries I'll be visiting(Serbia, Bulgaria, Macedonia,Romania, Turkey, Syria). Any advice is really appreciated, thank you! Siniša Glogoški