What?
The Confederation of the Rhine was pretty well liked from what i heard, they got modern thoughts into their states, and were aided by the French economically, all they had to do was supply soldiers to the French, but they would have to do that anyways for protection of the country, only difference was that they served French commanders. And there was no such thing as occupation in Saxony until 1813, but that was just because the army was stationed there due to the fact there was a campaign going on there. Before that Saxony had always been the most independent of the Rhine Confederation states, along with Bavaria.
Also i think it is pretty obvious who is going to win when it is 200 000 vs. 400 000, in fact many of the German soldiers had already tried selling away their weapons and equipment on the eve of battle saying that they wouldn't fight anyways and would surrender immediatly.
The German states switching sides had very little to do with Nationalism, barely any. It had overwhelmingly to do with the fact that everyone was just trying to get a better outcome for themselves after the war, instead of being annexed by power hungry countries such as Austria or Prussia.