What is the range of a C172?
How long's a piece of string? They vary wildly, anything from about 3 1/2 hours to 6 hours to dry tanks.
I've done the part UK-Austria a couple of times VFR, no big deal. Don't know what it's like further east. Of course, there are always exceptions, but CAS transit tends to be an issue mainly in the UK, on the continent you tend to get it w/o much hassle.
For coverage of Jepp VFR charts see
here.
One thing I'd like to draw your attention to is the ELT issue. Check what you need where. Mode S has already been mentioned.
Sounds like a nice two/three-day trip - enjoy!
