Humidity and heat on stealth grow

Hi there guys growing in a small cupboard and haven't got the room for a massive humidifier and heater! How do these stealth grows do it? I need something that will control the temp and bring my humidity up but needs to be SMALL! Like plug in type? What do you guys do and what will happen if I go without?

Cheers

all you do is get the proper CFM fan to keep upwith the size space you're in http://botanical.com/hydro/air/calculating_fan_requirements.html
the room that the cabinet is going to govern the temp and humidity of the cabinet if the airflow is correct, which isn't hard in my region
some places require dehumidifiers/humidifers

but trying to close a small cupboard and seal it may require co2 and other equipment, the fresh air is important and is alot easier to use house air to control grow room air