I have a wide range of calibres and do lots of fox control. I too started with 17 HMR. 117 foxes in my first year with it.
I now prefer my 243 over my 223 & 204. Trajectory wise there's not a fat lot in it for typical fox ranges between most calibres, but the devastation from the 243 is pretty brutal: They are all instantly dead. Very dead.
Buy 6 traps. Leave them in the shed for a few days, near the perimeter.
Then bait them with peanut butter, but do not set them.
Then set them all one night.
Other option is a dustbin (with optional water in the bottom) & a tipping platform, baited at the end. Use a small magnet to add a sudden (not progressive) tip.
It listens for the bang IIRC. It'll never manage to be very selective about whose bullet it's tracking. Will probably tend to pick up the signal from the bullet with the biggest/flattest tail (eidt: which is most perpendicular)
I've got Bushell Elite + IOR + 2x Swarovski (one illuminated)
This time of year all my shooting is with a lamp (wide range of lamps)
You can have a peep through them if you want to head down west....