>>1850543don't ditch the backpack. Put the laptop in the backpack and the backpack in the basket. Carry another layer of clothing at the bottom of the backpack for extra shock resistance.
The backpack with a vertical laptop in it will fit in your basket right? And a backpack is easier to strap down.
my favorite piece of kit is these prout lil grippa bungey cords that cinch down. hook bungeys do have their place but these are way more secure.