Washcloths dedicated to that use. We have different colors for bathing and bottom drying.
Mind you, you could use the same washcloths since they all get washed before being used again anyway, but it lets guests be less confused/bothered.
Now, I do tend to do a check with TP before going to cloth. After a while, you get used to how the stream feels when you've gotten everything washed away, but it's still a good idea to check. But for actually getting dry, it's cloth because TP just doesn't dry things well enough to preclude the extra moisture from being a possible problem.
We keep washcloths in the bathroom in a small cabinet beside the toilet. One shelf has the bidet cloths, and is labeled as such. There's a small hamper for them that gets emptied daily into the regular towel hamper at the washing machine.
Sometimes, guests that aren't familiar with post evacuation bathing can end up leaving a bit of residue, so that hamper load gets washed the same day when we have guests. But not everyone uses it tbh. We only have maybe five regular guests, and only three of those use the bidet. Well, if the others are using it, they aren't mentioning it and they're drying with TP despite the little instruction manual lol.