Hello Till,

I think the route Kyrgyzstan-Kazakhstan-(Ferry)-Azerbaijan-Georgia is easiest for a spontanuous travel, because:

Kyrgyzstan:
No visa neccessary

Kazakhstan:
No visa neccessary for a visit up to 15 days (up until the 15th of July). You can also find this information on the homepage of their embassy in germany: VISUM 15 days however, might be somewhat tight, so that if you have an easy opportunity to get a proper tourist visa (valid longer), that probably would be the better solution

Azerbaijan:
evisa, which can be obtained without sending or bringing your passport anywhere. You just have to send in a copy of a passport, a picture, the application form and a hotel booking conformation per email(!). I recommend Azerbaijan travel agency as besides just getting the visa they also helped us out with the hotel conformation (as we have none in advance as individual travellers). They were very friendly and replied immediately when we had questions about the Azerbaijan visa. This way you dont have to rush in 72 hours.

Georgia: No visa necessary as well, for example stated here: GEORGIEN Visum Einreise Papiere erforderliche Impfungen

I cannot tell too much about the Russian visa, but I heard that an overland transit visa is difficult to obtain (also it means again: rushing). Tourist visa is possible I guess, but I dont think neccessarily without struggle. So if I were you I would prefer the ferry. I would not skip on Georgia as I heard again and again and again that it is the most beautiful country of the Caucasus

Hope that helped.

Kind Regards,
Saskia (also from Germany )