I used them alot for denning fox and coyote over the years.One way door repeating capture traps work very well if you set them up properly. I still use them currently when needed.
Here are some photos of a trap I modified years ago for denning fox, coyote, badger,raccoon and groundhogs. These photos may still be in the archives.
I used a safeguard coon sized trap (11"x12"x30") as it wis large enough to work on all species I targeted. The mods are easy to see with the close up photos. It doesnt damage the trap so if you only have a few traps you can make the changes and remove them if needed to put the trap back into commission for regular single door captureing once again.
Just wire or zip tie back the locking spring to the cage door face which now will let the door move freely when pushed against. Once that is done I hog ring a door extension to stop re entry. I use vinyl coated 16 ga. 1" x 1" wire grid we use for barrier work as the best material for this application.You may need to make a nose cone or some such fitting or I have just dug out the den entry to fit the end of the excluder and filled in with dirt or used dirt filled feed sacks to barricade the device securely into position.
For those that may be a bit new at this, the door of the excluder is facing out when you mount the device into the den entrance. In other words the rear of this modified trap is now facing the den.
Once the device is positioned I place a golf ball under the corner of the excluder door to allow a space for the fox to use its nose to see there is room for an exit and they will test the door and the ball will roll away and they will be going thru in a jiffy into my holding pen or you may choose to exclude only.
You can exclude with this device however they may attempt to dig back in to the den depending upon their age. I attach a holding pen to the end of the excluder to hold a litter and the adults if they are all inside at the time of installation. If not I catch the adults with soft catch traps or cages with the pups together and take away for release if legal to another suitable area or release just off the property.They won't go back to the den site in my experience.
Its a done deal using these devices once you have had some experience with them.