I’ve never seen it but been told that Lairds used to build ramps partway up the outside of their perimeter walls to ‘collect’ more deer into the parks.
There are many types of one way access systems where the animal to be trapped/collected pushes on some swing bars (look up bob wires), a door or even a full trapdoor into a box. I’d go with this for your plan. Look up trapdoor rabbit trap. DIY it bigger and more sensitive and then twice or more times a day you check that the box contains healthy bunnies ready for release into your pen. Anything else can be returned to the wildside unless you’re also marketing mink and fox meat by this time?! You could build a little escape tunnel allowing any accidental weasels, stoats, roads, etc, access back to freedom.
Watch some YouTube videos of foxes to get an idea of how they behave and jump, or a wildlife camera and some bait at your site and start seeing what is there and what eats a chicken carcass (wire it to a post or the first fox will carry it off). To my mind you want the first line of electric fence before the fox even jumps; (maybe 1.5m away, maybe 18” off the floor). Because animals stung by a single hot line, especially if at the top, all too often barge through/flip over as they’re in motion already. Another 18” off the floor and 12” from the fence prevents digging. However you now have to guarantee the electric fence never fails. It fails due to energiser problems, battery problems, solar panel problems, slugs arching out the electric, rodents chewing on cables, water ingress. All vegetation needs to be kept away from the wires and any sticks/branches/similar which might blow down in a storm need to be removed ASAP. In addition, for a jumping fox, there isn’t even much chance it’ll get a shock as the pulse is every other second or so and the fox would fair likely sail up up and away without ever noticing. Also the better the kit the more likely it gets nicked. None of this stops stoats, weasels, mink, rats, buzzards or sparrow hawks (yes I had one which learned to stand on one leg and reach through the chicken wire to grab my chicks and pull through whatever limbs it could get).