can be done
went down last year, 6 days from UK, 5 from france side. Got to croatia coast on second evening, just below Rijeka. I followed the coast road south, but found the going fairly slow, lots of italian camper trucks going about 30km/h. Jumped onto the toll motorway after Sibenik to by-pass Split - gets you down close to Dubrovnik, which is worth a good look. After that, you're in Montenegro, which requires a green card, as do quite a few of the others. Mine didn't cover montenegro (I think the insurance company thought. Serbia and Montenegro were the same country), so minor hassle. Also, what the customs all want to see is your original bike registration document, so dont forget it. The roads are getting worse by this stage, and quite a few old soviet era cars. Anyway, its also getting cheaper and less familiar, but don't miss out on Albania. Great place and mental roads, especially to the south. Once you hit Greece the roads are all perfect, but can be expensive (tolls everywhere). 10 days would be nice, but 6 is fine. BTW, took me 4 all up to get back to Bristol, but not much sight-seeing.