Smart idea for now. No sense in trying to prove your dad wrong. In the meantime I would suggest looking at pedals and shoes for downhill or freeride mountain bikes. Between the pins and the sticky soles, your feet actually stick quite well to each other. I run clipless on my road bike and my cross country mountain bike, but on my downhill bike I use platforms and sticky soled shoes. I just want to know that I can dump the bike very quickly if I get in over my head. This is mostly mental, but seems to give me more confidence when the terrain gets nasty. That being said take a look at some of the low profile downhill pedals like the Azonic 420's or Deity Decoy pedals, and shoes by Five Ten. This combo really will reduce the chance of your feet slipping off the pedals.
http://www.azonicusa.com/azonic_2010_pe/index.html
http://www.deitycomponents.com/decoy_2_pedals.htm
http://fiveten.com/products/product-.../Freeride_m23/