I put a rug on before the rubbing starts and generally that is enough other than the face (she rubs the whorl area and under the forelock tho the forelock stays in). I don't like hoods in case an eye gets covered when I'm away from the house.
The mare I have with SI type rubbing history appears allergic to forestry blackflies the tiny ones as she didn't rub up at Aberfeldy last summer being backed even tho they have plenty midges and clegs

If she does rub here now I've lost the forestry field then I will use any kind of barrier to cover a rub so it doesn't get worse - oil or grease types are most effective, and Avon SkinSoSoft to repel insects (her and me both!). I am also trying Brewers Yeast this year as a supplement - B vitamins similar to what works with marmite.
And all the ponies are dosed with Spot On for general fly annoyance etc anyway..
I tried all the usual creams, lotions, potions and the SI injections from vets under the research trial a few years back that the boett folk did - nothing made any significant difference but if it wasn't midges she was allergic to then that might explain it