If’n I wanted to finish off your goal, I’d head for the Forest Service in the Ozarks, find me some clear cuts, and go to making fox sets. Make a vacation out of it. The Ozarks are a great place to visit lol.
I’d bet you could get a grey or two in short order.

See both reds and greys here in Central MO. Have a young cousin who just started trapping. He has caught 2 of each this season.

Ya around here wouldn't be long, with the hills, timber, and brush we have. Plenty of public land as well.

I used to catch maybe 10- 15 a year in Taney county. Life has gotten in the way and I haven't trapped much the last few years. We owned some land in East Lynn Mo and id go up and trap it and my uncle's place in lone jack. I always caught a gray fox or two at lone jack but it was more timbered draws than around East Lynn.