maybe if the bonus commandos was explored, a larger subplot could be introduced to replace/reduce the ewoks? if there is a larger rebel force, some event could seperate them into two parties, leaving the smaller party to finish the mission. it could be a second shuttle crashing, or failing to arrive. but it is generally assumed that the larger half is gone. the rebels get captured, marched outside and all seems lost. the battle starts as before (perhaps without the ewoks, just 3p0 causing a distraction). but theyre cornered and death is almost certain. the predictable twist later on would be the lost rebels showing up. maybe even using the shuttle's firepower to allow han and his few remaining troops to re-storm the bunker.