homemade incubator light bulb question

I built a incubator out of an old mini-fridge using the cooler-bator design from BYC. I lived in California and hatched hundreds of chicks. i have recently moved to Idaho and fired up my incubator in my garage. unfortunately, it is Feb. and freezing cold. so my incubator is having problems keeping up the temp. I was wondering if anyone with homemade incubators had tried using small reptile heat bulbs to heat their incubator.

I think that the large heat lamp bulbs would be too hot and intense. but maybe the smaller bulb would work.

Any ideas?