Venting my new grow box. HELP!

Alright so I've been growing outdoors for awhile and decided to start growing indoors. In my current housing situation, this is not easy and it has to be as discreet as possible. I got one of those big plastic tubs always used in storage. The tub is 24 inches long, 18 inches wide, and 16 inches tall. I got a GYO2002 4-Piece 400 Watt Hydroponic Reflector Grow Light Set. Obviously with the lack of height of the tub I'm limited to autoflowering plants and using low stress treatments on the non-autoflowering. I think theres enough distance between my light at the top of the tub to the pots down in the bottom, although I know its not optimal. However, leaving this light source in an enclosed box with my plants doesnt feel safe and Im scared it will not only hurt the plants but cause a fire. Please give me instructions on how I should go about keeping this box cooler, if I even need that as well as anything else I should know as a first time indoor grower, although I know a good amount for the first-timer. Thanks! I just wanna smoke.

yeah 400w will be wayy too much for a plastic tub like such,prolly pretty dangerous aswell shit id use a 150w hps or 250 with a cool tube on either one. got any pics of the box?