That’s what I use to sterilize stalls, buckets, everything. They use it to clean poultry farms and it’s safer to breathe then bleach mixture.
You can sterilize everything you can think of. However, the spores drop off the infected horse, and get everywhere, on the ground, in the air, in the arena footing which get airborne as horses get ridden, in paddock footing where horses roll, in brushes, on people, on tack, and you can’t sterilize a lot of this. And a single spore will, if given the right circumstances, will start a new infection. “The right circumstances” are the key. Usually getting onto the skin in the girth area, where they get pushed firmly onto damp skin is a scenario they find helpful (“girth fungus”), but can infect all sorts of places in an animal that is not already immune. Once an animal (or human animal) has had a ringworm infection, they gain immunity to future infections. So that’ the bonus. Because your horse WILL see ringworm spores, eventually. Or, if it is an older horse who has “been around”, it probably has already “seen” ringworm, and has immunity. Because the spores are everywhere that animals come and go.
In theory, this is true. However, in my experience, the spores like living in particularly attractive zones and don’t necessarily hang out forever everywhere that they touch. I used to work in a dairy barn. Only one area in one barn was affected. Young stock that hadn’t been in there before were almost certain to get it. Older ladies that hadn’t ever been in that area might get it if they hadn’t had it before. It never spread into the main barn, nor the other section of the affected barn.
So, while I would scrub the life out of my trailer and wash anything washable on hot, I wouldn’t spend too much time worrying about having brought ringworm into my horse’s environment in the OP’s case.
Yikes. I knew it lasted, but that’s nuts
“No good deed goes unpunished.”