R’ yisroel of vitznitz has quoted that the brisker rov zatza”l was reluctant to sign on the protest against giyus banot, saying that not only is giyus banot ossur, so is giyus banim.
In terms of who the gedoilim are, one has to rely on hashgacha elyonah that hashem gives every generation the right people, so if one sees that chahcam ovadia is treated as manhig by the sefardim, R’ steiman, r’ karelitz, r’ kanievsky and r’ aeurbach by the ashkenazim, and the rabbanim of the eida hachareidit and satmar by the kania’im, alongside the respective rebbes of belz, gur, and viznitz, one can rely on their da’at tora for our generation, even if r’ aron lichtenstein feels differently.
When the chazoin ish was asked for the source that giyus banot is forbidden, he opened his shirt and pointed to his heart. One does not need to see the sources, when one sees a person who has learnt torah passionately for many years – such as chacham Ovadia, – one can rely on their pure hearts a a source.