Just ordered a grow tent, need advice on lighting.

I purchased a 60(h)x36(w)x20(d) grow tent. a huge upgrade from by 3'hx2x2 box. My concern is that the area that i grow is subject to relatively high temps in the summer and very low temps in the winter. i've had pretty good results with my 135w led in the summer since there is low heat output. i'm hoping i will continue getting good results when i switch to the tent.

i want to get ready for winter so i was thinking of either using the led along with some cfls that would provide heat or i'm considering hps. whats a good size hps for that grow tent? should i get a cool tube? i was thinking of buying some auto seeds so that it doesnt get cold in the room since i could run 18/6 for the auto, keeping the tent warm from the light , unless i should just get a cheap heater.

I saw a youtube video of a guys grow under 180 watt LED and he said it had a light coverage area of 2x2 so you might be pushing your luck with a small LED in that 3'x20". I would look on craigslist of ebay for a 400 watt hps or maybe even a 600 with good ventilation.