Pretty much up to back/backwheel. Pedal hop is the same as a pedal kick (hopping forwards on the back wheel) and a tap is when you hit the front wheel into the object then launch up onto the back wheel.
If your dad is worried about your safety then he should let you grind the rim, purely for the increased hold you get, which will actually make riding safer.
But because theyre \__/ shaped the majority of the weight will be where the pins are, so they will go upside down to how they are seen in that photo, meaning every time you get on you will have to spin the pedal round.