I've not tied with otter but if I had one I'd certainly give that dense under fur a try as a dubbing material in something. Given the natural oils, I wouldn't limit it to just nymph bodies. I'd suspect, like mink, the longer guard hairs would have some usage a dry fly tailing materials.

With some of those guard hairs mixed in I'm sure you could get some pretty interesting and buggy looking nymph bodies. Might be some interesting blends from the mask (face) if you saved that section.

Give it a shot and post your results on in the Fly Tying section.