Don't go with the halogen, they are useless as plant lights. Worse than useless even. If you want to generate more heat then you might as well add more useful light, a couple more fluorescent tubes will generate about as much heat as the 60W halogen. If you really feel you don't need more light, then get a heater :)

Fluorescent lights will just heat up the area they are in, they radiate very little heat directly onto the plants. Consider enclosing the grow area if it is in a large room, with the lights inside the new mini-grow-room. You are never going to heat a large room with fluorescent tubes, not in a Wisconsin winter anyway. A heating cable will efficiently heat the soil from below but the air may still be too cold for the foliage. Metal halide lights radiate quite a bit of heat directly onto the plants, they are usually placed several feet away to avoid burning the foliage. But you really don't want metal halide lights for your little growing area. And remember that lighting will only keep things warm while it is on, not at "night".

Hard to give more specific advice without knowing the size of the growing room and the current day/night temperatures. It would also be helpful to know the plants being grown to see whether they would benefit from significantly more light.

Purchase another T8 fixture, and overdrive it so it will run hotter, heat your space, and also provide a LOT of much more useable light than a halogen. 3 overdriven fixtures will draw
over 324W and continuously this should help raise the temp. Also, I hang my garden so it is in the upper (warmer) air nearer to the lights. In my case I actually need to use a fan to cool things down, since I have 10 fixtures in all, and this draws up to 1080 Watts when overdriven, and 640+ Watts normally driven. After the electricity is converted to light and plant growth, then it becomes heat to heat my house :) Paul Mozarowski.

Here is a link that might be useful: overdriven T8 setup.

The setup is in my basement, which is about 1500 sq'. The max temperature reading is 71.6F / 73% humidity. The min is 57.9F / 43% humidity.

I don't think I can enclose the area entirely. I could wrap some foil insulation (bubble type) around the table, but I don't know how effective that would be considering that heat rises and the top wouldn't be covered.

I think my husband would kill me if I would even suggest leaving a space heater on while we're not home.

So a metal halide is completely out of the question? Are there any other options? Thanks for the help!

You can use a metal halide if you want, but don't tell your hubbie that it uses more juice than the space heater, LOL.

Starting at 400W, the metal halides are good for 20 square feet or more depending on the plants. At lower powers they get less efficient, you could use a 250W maybe.

Your temperatures don't sound so bad. Or are you growing really tender tropicals? Or is it just going to get a lot colder?!? It sounds like your main temperature problems are at night and the lights aren't going to help so much. If there is no natural light in the basement, you can offset the lights to be on during the night and then off in the afternoon or evening when the basement will be warmer anyway.

I agree with Shrubs_n_bulbs, your daytime temperature is pretty close to the optimum of 75 degrees, not really significantly too cool at all. It is good for the plant to let it cool down at night. Besides my initial advice, I would also get rid of the daylight deluxe
6500K has far too much blue, and replace it with a warm white lamp, like Phillips high output T8 available from businesslights.com for $2 a tube. They provide 3100 lumens.
More lumens = more photons = more high energy electrons = more growth. Compare the line source output and compare it to the photosynthesis action spectrum, and you will quickly see why I say this.
Paul Mozarowski.

Here is a link that might be useful: Photosynthesis action spectrum

I don't think you mean "high output". Perhaps you mean "high lumen" lamps? I also couldn't find any Philips tubes at the site, but you may be referring to something like these.