I would have thought that such a well respected and long established outdoors challenge for the young adventurer, would have had a set list for the equipment that each candidate was expected to carry.
Weight may be an issue, but firstly i would want to know which items of kit are essential or compulsory, and which are optional.
The main criteria for someone who is possibly new to the great outdoors, is staying dry, warm, and fully hydrated.
Correct boot fitment and comfort hopefully will be taken for granted, but there must be a specified kit list.
A 20k weight seems quite heavy, especially for someone possibly unused to hauling that kind of weight around on their backs.