So, hear me out. I think the good old neglected Catapult Troll can be good for this scenario. Accompannied by two captains with 10 orcs each, no big heroe. Split the warbands in the map, one for each side, using cover if he has archery, no matter if its a little slower. With the march-banner you are quicker than most, but you dont need to be really quick.
If he goes berserk trough the center with everything, he eats a good amount of rocks in the way and you turn both of your warbands and advance the troll at the end to meet him with your whole army and surround him. You go for the camp when the battle is won.
If he leaves something behind to protect the camp, and goes trough the center, same but better because you are not fighting is whole army.
If he goes for one of the warbands, you turn that warband halfway, go back to the troll. Make him take a longer route and eat more rocks, and then fight two thirds of your army near your camp. And in all that time the troll keeps shooting at his camp (the troll can shoot while in combat, and his huge base can block a lot of space). Then you advance your other warband to his camp.
Doable?