I have a couple of clever tricks to avoid the problem of having the heated vest and lights on at the same time.
1. I avoid riding at night (other than in city limits) because I don't like dodging kangaroos and other animals. Most of Australia's animals come out at night and are too stupid to get out of the way.
2. I don't own a heated vest, heated hand grips, or any other form of artificial heating. Don't find them necessary, even in Tasmania. I use the same heat retention system as whales and seals - a generous layer of blubber
Cheers,
Cam