The box on the end of the brood pen is 3.5×4' I would like to put a lamp in to keep it warm on these cold winter nights. I have pups due on dec 20 th. I went to famr store to ask sone questions and look at lamps but the associate thought the 125w lamps they carried would heat up to much and suggested a regular 40 or 60w light bulb. The 125w heat lamps was the lowest they carried. Any suggestions?