I have had great success with two females I got from a rescue. They were mostly feral and survived on their own for some time before capture. They could not be rehabbed to be house pets, so I got them FREE, with no adoption fee....fixed, all shots, etc. And I got two cats that knew how to survive traffic and predators and to hunt.
My instructions were to contain them for 10-14 days in the barn (that was challenging but worth it) with a litter box with Feline Pine or the newspaper one...Yesterday's News? A neutral, non-clay, non-clumping litter. I fed them a premium dry food, Evo. I wanted them sleek and strong and healthy. They had two weeks to get used to the sights and sounds of my property and become comfortable with it. I saved all the soiled litter up. When the day came to let them out, I sprinkled the soiled litter around the perimeter of the property where I wanted them to stay, basically marking the territory for them. Hence the specific types of litter...clay won't break down, those two brands will.
I still feed them the Evo. Not too many cats will choose dry kibble over fresh mice, rats, chimpmunks, and squirrels.
I've never had an altered cat spray. I have had altered cats get cystitis and think that the litterbox was the source of their pain upon urination, so they look for other places to pee. That isn't marking, but could be mistaken for it. Both males and females will do this.
My vermin problem sharply reduced since the cats arrival. I really like having the feral ones. There is no angst about bringing them in the house, and they don't follow me, bugging me to come in or get fed. I just see a quick little shadow at dusk if I surprise one while it is eating the kibble.