when i do mine we skin the skulls out right.
the dish soap is a good idea but in the future try using lemon juice.
i have also found it easier to pulll the skull out of the water every 20 to 30 min to peel more membrane and what not... this also helps to keep the weeker bone (nose and jaw) intact.

that being said those skulls you did look really good and you did just fine for your first attempt