What I have found is if you can keep your body core warm, and wear a good insulating coat and insulating pants, you really only need a heated vest and heated grips.
B heating your core, nearly to the point of being too hot, your body will respond and send that warm blood to your extremities and keep them warm.
What is nice is you don't need $1000 worth of heated gear, just the Harley vest and thermostat and heated grips. Nothing more to pack when not in use. Jacket liner may do the same thing.
Gerbing is probably state of the art. I have HD vest for me and lady on the back, can hook up both to one thermostat and separate control. I have HD heated gloves but have never used them, just too much heat. I have ridden Wichita to Dallas in 24 degree cloudy weather and was not cold. Not fun, but not dangerously cold.