Sorry about your muskrats.

A 25' tunnel is both impressive and infuriating.
There are some excellent trappers on the forum. Hopefully, they can further improve your trapping efficiency.
Is your location such that it is safe for you to also shoot muskrats at your pond? We used to never see muskrats while fishing until the wind would lay down a little before dark. I think a moving muskrat would be very difficult to hit with a .22. In your shoes, I think I could get some with my old .410 shotgun while there was a little good light remaining. Also, I would be much less fearful of ricochets travelling far beyond the pond only using pellets.
For the experts, is it safe/legal to poison muskrats? Needs to be safe from precious kids/dogs, etc. directly getting into the poison, plus safe from anything that might eat a dead muskrat and indirectly get into the poison.
Also for the experts, will a muskrat in the water have enough heat signature to trigger a game camera? Sure is easier to hunt/track critters when you can determine their pattern. If they don't trigger the camera, then perhaps you can get them using the time lapse function?