First of all, welcome Hendrik to the (small) world of Packrafting in Europe! 
You seem to be quite busy at the moment, but determined to go for packrafting nevertheless. Give me shout whenever feel like planning something.
It 's been a while since my last post. However, there has been some boating. Short report:
To start with, there was a 3 week biking loop traversing the eastern Carpathian Mountains, being part of five different nations (Slovakia, Poland, Ukraine, Romania, Hungary). We had the boats along and that resulted in:
- rafting the upper Tisze in Ukraine (bigger class II-III water): http://picasaweb.google.de/sven.schellin/TranskarpatienUkraine#5507893861420072354
- creeking the Vaser Valley in Romania (smaller class II-III Water)
http://picasaweb.google.de/sven.schellin/MaramuresRumanien#5507891758090916370 - bikeboating the lower Tisza in Hungary
http://picasaweb.google.de/sven.schellin/AusDenWaldkarpatenUngarnSlowakei#5507898247896612082
Although surly used, and that was fun, I would not take them again in that region in July. There is no real “need” when you are biking here. Always a trail or even a road existing. Water is rare in full summer. The relation of boating and carrying the boat was simply outnumbered. We travelled light and could afford it to pack them, but it was still a major part of our luggage. Biking over mountain passes would have been easier 
In contrast, we recently had a flush of high water in eastern Germany. Despite some tragedy for others in special places, it was pretty unusual to find paddling opportunities in the middle of August. It’s more frontcountry boating. But its boating!
http://picasaweb.google.de/sven.schellin/BahraBei10Kubik#
Last but not least, I went into playboating http://picasaweb.google.de/sven.schellin/ObereSpreeBei10Kubik#5507890222822794098
With the right spot, its ralatively easy.Try out yourself! Although you do benefit from thighstraps and other mods (secure spraydeck closure).
Sven