Some Help from the Pro builders please

Hello all. I just put together a wardobe closet I bought. Its 71" tall, 48" wide and 20" deep. I will be using a 400w MH/HPS with a 6inch inline fan to a air cooled hood and a carbon filter. Question is how can I make this closet more stable? It kinda leans forward a bit and i wanted to some how anchor it to the wall but didnt hear a stud in there. Reason being once i hang my big inline fan at the top of the inside and have the light and carbon filter hung i dont want to worry about it topping over lol. What do you guys think I can do?

First pic shows it gets farther from all as it gets taller:

Anyone? Any ideas might point me in the right direction. I am just looking for a way to anchor the top so it doesnt tip over. Any ideas? Maybe put a s hook on the top and a s hook on the cap and use a hardened bungiee?

Tilt it back just a fraction with a small piece of wood and put some heavy shit like weights in the bottom or
if you have legs on it cut a piece of wood to fit snug between the back legs screw the wood to the floor and than the legs to the wood or get some wall anchors, they have ratings on them and are easy to use.

Peace