I have trapped quite a few cats in box traps and I think they are much easier to set up than a leg hold but it takes a lot more room to get the same amount. A 10"x10" is plenty big for cats. They are used to crawling into brush piles and such and do not mind a small opening. I set them with the wind blowing from the back toward the door. Duck carcasses or beaver meat wired to the back of the trap work best for me and then use I some Milligan Brand "Cat-Man-Do" scent on a stick hanging down by the duck carcass through the top of the trap. Brush it up with cedar branches so it looks like a brush pile. Try to push down on the trap and move it back and forth a little to get some dirt pushed up into the wire so they are not walking on wire. Make sure nothing can block the door from closing. I keep some goose down in a zip lock and sprinkle some in the cedar branches over the trap so they move around in the wind to get a cats attention. The hardest part of trapping cats is keeping the trap open so that when a cat comes by he can get into it. You will have to catch all the coons, possums and skunks out before you get the cats usually. Also, there is a guy who makes box traps and they are really good and pretty reasonable. A lot better than the ones you buy at Atwoods. I have made some myself but it is a lot of work. If you want the guys name, I can come up with it. Let me know. Good luck and I hope you get some.
I'd be interested in knowing the guy that makes the box traps with a cage in the back. We are seeing lots of cats in our bird hunting area this year.