Opossum's eat ticks. I need all of them here the habitat will support. Coons are to me not a problem as far as I know.
Opossums may eat ticks, but they are the primary carrier of EPM (Equine Protozoal Myeoencephalitis) which destroys a horse's nervous system. It's a fatal disease that has no treatment and is absolutely the most horrible way for a horse to die.
I've lost a good horse to EPM and I don't even want to see that again.
EVERY 'possum must die...
As to traps, I'm a huge fan if MB550's with cast jaws.
I also use Victor #3 longsprings because that's all I had before I found the MB550's.
When you first get new traps, put a cup of liquid septic line cleaner in a 5 gallon bucket of water and soak the traps overnight. Pull them out, rinse them off, and neutralize any remaining acid by dipping them in a baking soda solution (1 cup/5 gal water), then dye and wax them.
Minnesota Trapline Supply is my go-to for supplies.
I do predator control work for a living.
Not all traps come from the factory ready to go.
With the exception of the latest batch of MB550's, every trap I have ever used needed some sort of tuning.
The trap dog modification mentioned earlier with the notch in the dog and the pan is the best way to create that crisp letoff with sufficient tension to avoid rats and rabbits from setting off your traps.
To make sure you're getting the proper pan tension, pay a few bucks and get a pan tension guage.
I set mine with ~3-4lb of tension, depending on which trap I'm working on.
Ed