Petzyme is available in 1 gallon size and also smaller spray bottles. It usually helps. I hate to say it but a catch alive trap will work the best. Catch the cat. Call the owner so they can see what is going on but give them warning. If you continue to have trouble catch him again and call animal control. I used to think I didn't like cats. I have learned I mostly don't like irresponsible cat owners. : ( TAria
On the wood part, the best thing I know of is an enzyme-based odor eliminator. Nature's Miracle for Cats works pretty well. It's not a cover-up, the enzymes break down the bacteria that's causing the odor. For it to work, you'd need to soak it, and keep it damp for at least a couple of days. To prevent a repeat performance, Polly's suggestion for moth balls sounds good to me. Like she said though, they're very toxic to animals, the strawberry-container suggestion sounds good also. I had a neighborhood cat get into my car once and spray. P-U. The heat makes the odor even worse.
Sherry