how do you manage to get pebble hidden perk

[Cyrus]

I got the hidden perk by the time nebakov ambush, but i clear all existing side quest and activities, almost.

However, i spend 30 % time with another horse and buy back pebble
Last night I found it less exhausting to achieve 35km ridden distance by using the follow the path option and afk, let henry and his girl roam the Torsky map

how do you get this hidden perk, as far as i know , fast travelling does not count to the 35KM distance?

[Arden]

Ride the horse. I don't use fast travel and unlocked it pretty fast and maxed horsemanship before the hypsy riding contest.

[jaclaffite]

Fast travel does not count, you need to ride the horse for less than 35 km (I got it at ~34.87 km total ridden distance - and this distance was probably not ridden with Pebbles alone).

It's not so long honestly, given the distances you have to travel in the game. I got the achievement in the first map.