Do not encourage people to trap and release vector animals! You soft hearted law breakers just pass your problems on to someone else. If you can't handle dispatching predators get rid of your chickens. To the OP opossum are not too bad to get rid of and I haven't seen them do the destruction that other nighttime predators do. Worst I have had is trashing a nest of eggs under a broody. Trapping and killing the pest is the best way to end the problem because it looks like you are not able to securely lock the birds up behind almost solid wood at night. I am leery of the quality of craftsmanship of the prefab coops and would do the double wiring like another poster suggested.My husband put hard wire under the coop and brought it out about a foot past the edges ,he bent it down into the ground and covered it with dirt. We have coons and possum and they never ate through the wood. Buy a live trap from tractor supply and put a dish of cat food in it ,we've caught family's of both nite after nite. We then take them 6 miles away and let them go