I think woodchuck is pretty good, simply cannot bring myself to contemplate 'possum. They're evil and super-natural little fucks.
I catch possum in live trap. Put 4+ pellets into the head at close range - thru & thru. Dig hole, go to move trap - it's up and hissing. Few more shots, dump in hole. Fucker come's too and starts climbing out. Wack-a-mole with shovel - fill hole. Dirt starts heaving over the hole. Fine.
Park diesel tractor back tire over hole.
Come back in morning - hole dug at about 45 degrees from under tire. Possum gone.