Or just avoid the clunky wording with [t]he Principal Contractor must be satisfied that the are no major cables in the vicinity of the works or similar.
I think so. A lot of the problems with gender neutrality do seem to be capable of resolution in this way - i.e. avoid backing yourself into the corner of needing to use a gender-sensitive pronoun, rather than using a clunky way out of it.
Whilst I can see the point behind gender neutrality, I do wish we'd managed to introduce proper gender-neutral pronouns, rather than damaging the language by removing a useful singular/plural distinction. Has something similar happened in most (Western) languages, does anyone know?
It's also slightly perverse, of course, that it's not that long since the truly gender-neutral "one" passed out of common usage. "When acting as Principal Contractor, one must be satisfied that there are no major cables in the vicinity of the works" is entirely gender neutral, but somehow seen as a rather snobbish way of writing.