You can only fast travel when there are no enemies nearby and using the scroll menu and click on return to hideout. The map should come up and you left click on the hideout you want to travel to.

How do you fast travel? I have two hideouts.

To set up a hideout, you have to find a hidden camp, which is normally 2-3 enemies around a camp fire. The fire may not be easily visible in long grass so turning terrain detail down in video settings will reveal it.

Single player. How do you set up a hideout. There is no "fireplace."

Nice.