Just a tiny blinking red light on the spoiler's manual switch will come on when you reach approx. 65 mph, and it will continue to blink until you turn the car off. I never even notice mine blinking at night, because of its low location. If it bothers ya, a 1/4" square piece of silver duct tape will cover it, and blend right in with the switch.
Or you could install a by-pass on/off switch directly to the fuse box and run the switch into the car like I did, then you can raise the spoiler at what ever speed that you want to. Total cost, just a few $'s for the switch and in-line fuse from Radio Shack.