Not sure who sells these hedgehog brush heads but they would be perfect, maybe someone else might, not sure how you would be able to connect it to carbon gooseneck tho,
He Man would know am sure he had sutton up a while back about this, maybe using a long reach resi neck instead of carbon would allow u to have a brush on either side
Gardiners had it were u could have a plastic scraper to flip round to, I suppose u could work on that basis and cover it with a sponge or sutton