the substrate temp is actually more important than air temp.. so get em nice and warm before painting, (maybe store em in a nice warm place of the house prior to painting them than put the light on em in the garage).... than back the lights off a bit for a more ambient drying once shot...
remember, the lights not only warm the part/paint, but remove moisture from the air/surface..
I remember back in the lacquer days, you'd paint something on a humid day, it'd fog/milk up, put a heatlamp to it, and you could watch it cook right out of it...