Well, we left the live trap, baited and ready to go, in our garage for 5 days. The little guy was definitely not in the garage. We even baited the trap with canned cat food the last 3 days; according to this website that is a opossum favorite.
Our garage still doesn't smell so good. I guess it's time to do some spring cleaning and scrub the floor. First, I need to get a storage shed built in our backyard, if I can get our homeowner's association to approve. I think I might try to run for a board position....that way I can try to dissolve to whole thing.