I know fishers like beaver flesh. Would chunks of beaver tail wired into the box work as well?

Caught them using beaver, venison, muskrat, squirrel, hunks of just deer hide, etc. But yes, fatty beaver tail would work I think.

You get them to the set and they see a hunk-o-meat, they don't care.

That's how I bait my KORO traps for fisher, slice of beaver tail through the bait holder. Also add some lure.

Not as well

I usually save quite a bit of beaver meat in the spring. I use it for fisher, cat and weasel. But have also caught fisher using fish heads also. I think anything that is meaty and stinks a bit.