After progressing though the story a bit, you will be tasked to scout out new potential Home Bases with Lily's brother. There are 2 options, a pretty large residential home with a closed off backyard or a huge trucking depot with a very large fenced off area. The trucking depot requires 12 people but is by far the better option and is the best Home Base in the game.
Press and hold down on the d pad to radio in your group and relocate to the new spot. You unlock the achievement once the choice is confirmed.