Ahh, very very good!

What I'm aiming though if for a indepedant Germany, unified by a power thats not Austria or Prussia though, so I still need Napoleon to be defeated...
Hmm, would it be possible for the most part of your plan Saepe Fidelis, to suceed, but before he can completley break Russia die from some sort of accident? How much confusion would this create in France and within the high command?
Well the plan hinges on having minimal interference from Britain. The fact is that Britain wouldn't want:
1- Napoleon with France and the HRE under his command, having such population and industrial potential would make him virtually unstoppable.
2-A Catholic power, presumably the HRE would still be Catholic and its strengthening at the expense of Prussia and the Protestant powers.
If you want a German unification, then how about this:
Bavaria, being mainly Catholic and close to Austria, sides with Napoleon and following the collapse of the Austrian Empire in 1810 and the dissolution of the Hapsburg Monarchy its King is made Holy Roman Emperor andbecomes a French protectorate. Meanwhile, 'Germany' is split between the Confederacy of the Rhine, a new Austrian kingdom which controls Bohemia and Silesia and is under the command of Napoleon's brother.
Prussia is eviscerated by Austria and Poland as it is reduced to its 17th century borders. The Hohenzollerens are stripped of their crowns and robbed of their Electoral seat.
With Bavaria leading the HRE it exploits Britain's blockade of France to sell iron etc. cheap to Napoleon, takign credit as well. Napoleon meanwhile masses an attack for Russia set to be made in 1815. He ignored Spain, signing an unequal treaty agreeing to prop up the existing King which all but opens Spain up for French occupation. Britain stations troops in Portugal.
1815. Napoleon invades Russia. With 1.5 million men he marches to the gates of Moscow and burns the city to the ground, leaving only the Cathedral and St. Basil's. The Tsar is forced to retreat and a resistence is organised. Looking for allies, he casts around Europe. InWinter 1816 an alliance is signed. Bavaria, Prussia, Poland-Lithuania, Britain and Russia all jointly declare war on France. With the army in Russia and under winter quarters Eurpe is undefended. The Duke of Wellington invades Spain and swiftly topples the King and the French presense there.
Bavaria, meanwhile, crushes Austria and occupies Vienna. They then rush north through the Rhineland where several great battles are fought. Finally they link up with Prussia's army under generla Blucher, and they defeat Marshall Ney and occupy the Rhineland.
Napoleon, meanwhile, forces his army back through the winter. He loses some 370,000 men to cold and cossacks. The rest swiftly crush Poland-Lithuania and Prussia, its forces in the west, is defeated, with Konigsburg burnt and Berlin occupied. Napoleon marches through the Prussian heartland where fierce resistence is encountered from the Junkers and the Landeswehr units, militia trained in guerilla warfare. The Emperor is struck by a bullet and killed.
The end of Napoleon in early 1817 brings a premature end to the war. The final status quo has only two winners. The first is Britain, who takes India, Gibralter, the Balaerics and obtains a protectorate over Egypt (the Ottoman Emp. had allied with Napoleon.) The second is Bavaria, who gains large amounts of land in the Rhineland, the Confederacy of the Rhine signing its independence away at the Council of Vienna, where a new Europe is hammered out.
Bavaria establishes its hegemony over Germany and Prussia too is forced in. With massive losses, including her own king and her finest generals she is too weak to fight on. The new Polish-Lithuanian Commonwealth is too strong for her even ,and a brief war in 1819 proves this as Berlin is besieged and Poland seizes the 'Polish Corridor'.
Most surprising are two things. The first is Russia. Having lost so many men and so many cities she is in no position to make demands, and Britain refuses to back her claims in Poland-Lithuania. She is forced to cede her lost territories to the new Commonwealth, avenging herself i nhe Balkans where she takes Moldavia and establishes proectorates around the Danube.
The second is France. With considerable military might still at her disposable, the treaty made is not as stringent as it would have otherwise been. The Tsar was keen for France to be dismembered between a new Burgundian kingdom and an enlarged Netherlands, yet such suggestions were dismissed. France obtained, finally, its 'natural borders' as the Rhine was made a frontier. The government was in turmoil, however, as the generals fought for supremecy. It took Bavarian adn British steel to impose a peace. The so-called 1818-1821 civil war was ended by a Bourbon restoration. Louis XVIII was crowned King in Rheims in 1822.
Bavaria would go on to industrialise throughout the mid 19th century while bringing more states under her control. The continued Holy Roman Empire was abolished in 1849 after Nationalist uprisings across Europe. It was replaced with the German Confederacy, led by Bavaria with a limping Prussia a shadow of its former self. In 1856 Prussia, Saxony, Austria and Westphalia formed the Deutchesbund, which was meant to be a counter-balance to Bavaria. War was declared, and in 1856 an alliance was signed between Poland and Bavaria. A two-pronged attack saw Austria and Prusia crumple. The rest fell into line and finally in 1858 the King of Bavaria was acclaimed Emperor of Germany and the Second Empire announced. East Prussia was ceded to Poland yet Austria, Bohemia and Moravia were brought into the fold.
Is that good enough, I whacked it out in a few minutes. This is actually a pretty good idea, if you're writing a TL I'd love to contribute.