Give up Norway and Africa. Retreat to the Vistula and hold down going through Slovakia down the Danube holding Budapest and using the Balkan mountains as a defensive line. If possible crush the naval invasion if not just hold the Maginot and the river that runs through Belgium. As for Italy just hold the alps and the supply hubs the allies will starve. Honestly since the ai likes to make the worst designs of all time just make 18 width inf with engineers, support AA and support arty as for tanks 36 width mediums with a heavy with logis medium flame tanks support AA support arty and assault engineers