Thats very doable in that time without too much of a rush.
I’d consider knocking off Poland though, and maybe Netherlands too.
For me, straight through Belgium & Luxumbourg, few days meandering down the Moselle ( Trier to Cochem say) then fastest route to Austria. I personally wouldn’t bother with Vienna, heading north to Prague instead, there’s a great little campsite in Prague with a good bar, about 20 mins from centre.
Then north towards Dresden, but venturing into the Saxon Switzerland National Park, which borders Czech and Germany, stunning area, but it will be fairly crowded, still really worth seeing though. Me, I’d stay there till the last moment, rush back on last day and probably miss the ferry
Saxon Switzerland National Park, Germany -- National Geographic