Weed needs oxygen and co2 to grow and metabolize nutrients and light. Air has both of these things. When you grow in a sealed box (no ventilation whatsoever) the plants will consume these elements and gradually decrease (mainly c02 during the light cycle) the concentration of C02 in the air will decrease and slow the growth of the plant. Therefore if you want to grow healthy plants you need to exchange the air in the grow room with fresh air to keep the plants growing.
The bad news is that without alot of special equipment you wont be growing in a sealed environment. The good news is that its going to be very simple to exhaust it.
You are going to need.
1. A source of suction, I suggest this as the bare minimum for the lowest cost.
Valueline Blower
You then need a carbon filter, I suggest you build one yourself. Not a crappy stuff a bag with carbon filter but a 1-2" long 8" tube that diffuses air through 2" of carbon.
Now you need a HID light from HTG supply.com Get whatever you feel comfortable with, bigger is better, air cooled hood is very important.
Thats going to be 500 -600 all together (400 for light system, 70 for a carbon filer 70 for the blower and 50 bucks at the home depot) for everything youll need. Cover the inside in black plastic on all sides, Mylar/visqueen/fylon the walls. Then in the other chamber (rest of the trailer) place your carbon filter and connect that via a tube to your light. Get a small duct fan and hook it up to an intake in the ceiling. Sounds like an ultimate grow box, am I being unclear?
Back to the subject your small duct fan will take fresh outside air and dump it in your growroom, the air is exhausted past your light, cooling it, then through a carbon filter taking the smell out, you dump the used air in the rest of the trailer to let the carbony smell dissapate and leave room for an ozone generator later, sweet.
