One fundamental problem: dad figured out what the son should take; the son should have figured it out for himself (dad could help and suggest, but son should make the decisions since he's the one who had to carry and use it.)

Dad may very well have known his stuff - but son clearly didn't.

Too bad someone didn't enlist dad as an assistant Scoutmaster (or backpacking merit badge counselor), so he could have gone along and shown everyone how to make the lightweight principles work.