Use the Support defence and Victory or Vallhalla missions to stall the soviets to a crawl, and make all your panzers in divions of one, motorised in groups upto three, that way having a single panzer and a single motorised corps attack gives you combined arms bonuses in attack and defence, and panzer is fast for defence especially when used as a mobile reserve rather than frontline troop ( put panzers in one province behind the frontline and use the reserve mission, they will automatically go using support defence to the frontline provinces that the province they are on borders), and have fun.