although hair covering is daat moshe, where does it say how much has to be covered? is there an opinion that if more than 51% of the hair is covered it is enough to be considered covered according to daat moshe?

Shalom, Daat Moshe is only relevant to whether a couple should get divorced but according to the practice of halachah there is no difference between Daat Moshe and Daat Yehudit and we have to keep both, meaning that a woman should cover her hair and may leave a small amount uncovered. The exact amount is dependent on the custom in each place. Kol Tuv