I have spent years trying to come up with a dog-proof fox set. I have used the old "mound set" but it is nearly fox-proof as well as dog-proof.
I have finally stumbled onto a set that works. I am still perfecting the bedding of the trap; it can be difficult. Also, this set requires vehicle access to the set location, it can't be done walking in.
As in any trapping: location, location, location but the very nature of my development makes for a very mobile set location.
Also, this set is not for use or sale within 500 miles of me; or maybe its 250 miles, I forget which. Anyway, use as you see fit.

a glue trap would bed easier, lol

A sunroof with a nitelatch and a reset spring
A colony fox trap

Like the repeater.
Reminds me of an old boy and his first new vechile.
Kitty kept climbing on it and scratching it.