Hi Sailboat, I don’t know what drowing is like. But, ACO sells an exhaust boot that attaches to your car exhaust with a hose clamp, and you connect a garden hose to it. Using car exhaust puts them to sleep, and is vurtually painless. So, build a box about the size of a dog house with the hose already in place. Put food in that box, set up a remote door closer system of somekind. And, as you warm up your car in the mourning to go to work take them out. Also, if you find their nest, you can slip the hose down the hole, and does its work.
By the Way, have you tired marking your property with dried blood? You can get it at most nurseries. The animals sense the blood and thinks something has recently been killed by a prediator and they stay away.