A knot that can be tied while the line is taut.

Yes! Except that loop is one or more Round Turns, and you secure with Half Hitches. One modification, if you can’t get underneath the wire to tie Half Hitches, then raise the base on that axis by using a thick washer/spacer or something.

By the way, you should experiment with making tension in rope by using RTs. It’s a fundamental concept. Knowing about RTs in rope is analogous to knowing how to purify water or make fire in camping. Learn it in and out.