I agree with the guys above - sooner or later shooting head backing
will tangle quite badly, and there is not much you can do about it.
I have tried buying dirt cheap 30lb or so mono and replacing the backing frequently, Shakespeare Aerial red sea fishing line was one. Worked OK up to a point. Lately I have followed Jim's suggestion and am trying Airfo Polyshoot (thanks Jim) and early results are quite promising.
Other than for achieving extreme distance and/or depth, shooting head applications on UK stillwaters are somewhat less popular then they were when Richard Walker and Geoff Bucknall were promoting them. Heritage flyfishers may recall the best shooting head backing ever, Don's of Edmonton's blue "Tapeworm" ie specially flattened mono. But that's not been around for years and years