As I said
Day 1 for the OP bod is too long and fraught with danger and frustration
Doable - but something I would rather avoid on holiday
If they want to do it the cheapest way, maybe
They should fit tacho’s to bikes and enforce rest stops if bods want to ride excessively long days
We have all done it in the folly of youth
But you are not him or them, JB.
Re-plan his holiday for him