I like the daring of it -- it's like 'get to Stalingrad before winter!'
I would definitely agree that you want to shift more armour down south - two Pz groups will give you great C&C; I'd add a third rail unit too - the one from AGN has probably done its job now and can get your supply lines working faster, especially if Odessa is going to take a while to fall.
He might have abandoned the Crimea but one option could be to try and isolate it from the east... if you can get good infantry (the mountain units probably) down over the Don south of Rostov you could be able to take advantage of the better weather down there towards the end of the year.
If you can create a large enough bulge to the east... even as far as Boguchar? it might buy you space to then use the panzers from south to north in 1942....
I am a northern front fan myself so will be fascinated to see how far you get.