first off , love the cabnet, but i think its a little small for what you want, the pic you posted of the tent . the tent is probly 6-8 feet tall. so your going to have to grow some small plants or a good sea of green. i threw together a cupple of pics for ya, of what i think can be done with it. if you really want some 2 ft plants you are going to have to scrap the top shelf idea.
here is idea one, what i think you are looking for, but like i said your not going to have much grow room with the light in there and the shelf, every inch adds up in a small space now if you plan on going streight to 12/12 light.. you are going to have to let the plants veg for a week or 2 till there 3-4 inches tall with some nice leaves on them before you put them to 12/12 and remember that they can dubble to tripple in size whell under 12/12. witch is where your height restrictions come in. but here is what it could possibly look like.
make sure the intake vents are at the bottom, close to the plants to maximise cold air and co2 gettign to the plants. on the other hand make sure the vents for exause are as high as you can get them in the box .. because hot air rises. i dont really know what elce to say about it. i hope the pic can save me a thousand words. if not let me know and i can break it down a little more for you.
now if your willing to loose the top shelf you can get a bigger yeild with your plants by letting them veg a little longer, with this cab, you will pribly beable to safely hit the 2 ft mark without risk of burning you plants with the lighs *remember they give off a lot of heat evin with the cool tube*
this one is as basic as it can get. and with a seprete veg chamber *ie a rubbermaid container and some cfls you can really max your yeild.
here is the bare bones
i wis i could stay and give you a little more info. but i have to jump in a shower and go out.. i spent all my time making the pics instead of explaining them.. if you have any questions or comments about the cab just ask or shoot me a pm and we can work somtign out good luck and i hope i helped a little