Not one person has brought up extended spring training. This is made up of players not assigned to any team. That can be up to 2 months. Players get no salary, but room and board and a small per diem for a third meal.
As an FYI and since I am not afraid to mention ever that i had a player in professional ball, during short season he lived with a host family for 50 a week. Being a college player on his own for 3 years he hated it. But because in the lower levels you can move up quickly and its only for a few months it works.
As far as I am aware, mlb is not involved with living accommodations but rather the team affiliates, if not owned by the parent team.
BTW, if you get traded and need something, there is always a closet full of stuff when you arrive, of things left behind or shared by other players. And as I mentioned once before here on another topic, the local sports store will be more than happy to help you out, with or without an agent.
No doubt lots of planning and budgeting is needed, but from what I know, the local casino or bar will get your money.
That's why you need to understand what's ahead, so that you can guide your player to make the best decision.