We did that so many times as kids.
My mate used to tie his 10 foot punt with 4hp to his BMX and ride to the boat ramp. He was about 13 or 14, the coppers pulled him up once, they loved his ingenuity but fined him for no helmet....
I'll have to see if I can dig up some photos of how we do beach launch and retrieval up north at low tide. It usually involves pushing boat and trailer across 100m or so of dry sand bar and using the anchor rope as a winch extension for retrieval.