helmet + clothes - bike shorts
Seat and bike shorts.
An integral part of biking comfort.
After all 6 hours a day are spent sitting on your arse.
Recommended: an expensive pair of professional bike shorts with substantial padding. That way you don’t suffer chafing from any seams.
Then you won’t complain about your sore arse even after 8 hours ride on a bumpy road.
PS. Don’t know if this is obvious but take another pair.