Thank you all for the input! I will definitely give it a try. Anything I get will absolutely be fixed. How quickly those things can multiply blows my mind lol. Not happening on my watch!

I second the poster who said get littermates. We have six cats now but have had as many as nine at once. We spay and neuter, and I've never noticed any of them peeing on hay. But they have gone in my trailer and used the shavings before.

Just wanted to throw this out there.. I actually got two feral cats for my barn through a local feral barn cat rescue near me. They provide everything and the cats are even spayed/neutered and have all of their shots and the best part is they were free. I’m not a fan of cats but I started to develop a rat problem in my barn and was sick of trapping them and laying bait.. so the fact they don’t like people is a big plus for me and my allergic boyfriend! I was able to get two males, the only slightly annoying part is I’ve had to keep them in a large cage for 4 weeks in order to acclimate them to my barn before releasing them but other than that I think it’s a great program to look into!! 

When the toms cats are peeing on your hay they are really spraying their scent marking their territory and its really a horrible smell. Get the boy cats fixed at a young age and then they wont do that, but if they get older and start marking and when you do get them fixed they will still mark territorys not all of them will but some still do. So getting them fix as young as possible will be a big help, I get all my males cats fixed at around 5 months are younger and never had them spray.

As long as you get the males neutered, they shouldn't spray on the hay.  I can't imagine the headache that putting a huge litter box outside would create!