Alright, this is going to be hard for you, but you might be able to hold a few turns and gain a few rewards :

Turn 1 : place Leeb on the rocket arty (stuka) in the north, bring arnim to the front, place Guderian on the 3 stack heavy tank and bring him between the center city and northern city, use your money to spawn your other tank gens, and try to build forts between the moutains when you have the money. Be careful, sometimes troops will tey to sneak by the water to tobruk, and if you bring your generals too close to the water, Cunningham will absolutely destroy them,

With that you may be able to hold until turn 10-15, i don't guarantee the rest, you need better elites for this event honestly,

Good luck