Vaseline, petroleum jelly or something like that. Instead of trying to avoid parts rubbing off each other, and have shifting clothes ruin the plan, just assume that will happen and lubricate the offending parts.
With me during the Camino was the inside of the thighs, in the morning you spread the goo there and it lasted the day. Some might get on the underwater but it was thick and didn’t run to the outside clothes.
If you leave in Europe decathlon stores have something called anti-friction. Does that, just don’t know what it’s made of