Insert a stormtrooper impaled Cannibal Holocaust-style into the background of every Ewok village shot.
Actually, I think making the Ewoks a bunch of bloodthirsty critters would make their victory over the stormtroopers a lot more interesting and believable. Sure, it will never happen due to the PG rating, but making the Endor battle R-rated would honestly be an improvement.
I’m just imagining the Ewoks building entire structures out of stormtrooper skulls, along with stormtrooper armor trophies and captured/tortured imperial officers begging the rebels for escape.
The idea of the Endor conflict being a brutal stalemate between the Empire and the Ewoks would certainly add to the Vietnam War parallel.